[ADD] port patches: gcc front ends, binutils gold, libtool multilib

Three more upstream PKGBUILDs assume x86_64, each in a different way,
and each is dropped rather than repaired because the thing being
dropped is architecture-specific by nature.

gcc: Ada and D are written in themselves and need an existing compiler
of the same language. Ubuntu ships gnat, but not one GCC 15 accepts,
and there is no D bootstrap compiler here at all. Modula-2 and COBOL
have the same shape. Front ends reduced to c, c++, fortran, lto, objc
and obj-c++, which is everything this port and ERPLibre compile.

binutils: gold is x86-centric, deprecated upstream since 2.44, and
built by no distribution that ships s390x. ld.bfd is the linker on Z.
binutils builds once gold is disabled -- measured.

libtool: the lib32-libltdl split package is i686-on-x86_64 multilib.
Its build step is already guarded by CARCH, but prepare() copies the
tree to src/libtool32 unconditionally and the package function then
packages a tree nobody built.

Two host-layout bridges were also needed. Ubuntu multiarch puts asm/,
bits/, gnu/ and sys/sdt.h under /usr/include/s390x-linux-gnu, while
glibc builds with -nostdinc and expects the classic layout:

  fatal error: asm/errno.h: No such file or directory
  fatal error: sys/sdt.h: No such file or directory

Symlinks make the host look like Arch for those paths. sys/ needed the
files linked, not the directory, since /usr/include/sys already exists.

--- FR ---

Trois PKGBUILD amont de plus supposent x86_64, chacun a sa maniere, et
chacun est retire plutot que repare : ce qu on retire est par nature
propre a une architecture.

gcc : Ada et D sont ecrits en eux-memes et reclament un compilateur
existant du meme langage. Ubuntu livre gnat, mais pas une version que
GCC 15 accepte, et il n y a ici aucun compilateur D d amorcage.
Modula-2 et COBOL posent le meme probleme. Les frontaux se reduisent a
c, c++, fortran, lto, objc et obj-c++, ce qui couvre tout ce que ce
portage et ERPLibre compilent.

binutils : gold est centre sur x86, abandonne en amont depuis 2.44, et
construit par aucune distribution livrant s390x. Sur Z, l editeur de
liens est ld.bfd. binutils se construit des que gold est desactive --
mesure.

libtool : le paquet scinde lib32-libltdl est du multilib i686 sur
x86_64. Son etape de compilation est deja gardee par CARCH, mais
prepare() copie l arbre vers src/libtool32 sans condition, et la
fonction de paquet empaquette ensuite un arbre que personne n a bati.

Deux ponts de disposition d hote etaient aussi necessaires. Le
multiarch d Ubuntu place asm/, bits/, gnu/ et sys/sdt.h sous
/usr/include/s390x-linux-gnu, quand glibc compile avec -nostdinc et
attend la disposition classique :

  fatal error: asm/errno.h: No such file or directory
  fatal error: sys/sdt.h: No such file or directory

Des liens symboliques donnent a l hote l allure d Arch pour ces
chemins. Pour sys/ il faut lier les fichiers et non le repertoire,
puisque /usr/include/sys existe deja.

Assisted-by: Claude Opus 5

patches/pkgbuild/binutils.sh

@@ -0,0 +1,16 @@
+#!/usr/bin/env bash
+# binutils: drop the gold linker.
+#
+#   make[1]: *** [Makefile:6798: all-gold] Error 2
+#
+# gold is x86-centric, deprecated upstream since binutils 2.44, and it is not
+# built for s390x by any distribution that ships this architecture. Nothing
+# links with it here: ld.bfd is the linker on Z.
+#
+# Dropped rather than debugged, because fixing gold for s390x would be work
+# spent on a component upstream is removing.
+set -euo pipefail
+sed -i 's/--enable-gold[^ \\]*//' PKGBUILD
+sed -i 's/^\(\s*\)--enable-gold.*$/\1--disable-gold \\/' PKGBUILD
+grep -q -- '--enable-gold' PKGBUILD && { echo "binutils: gold still enabled" >&2; exit 1; }
+echo "binutils: gold linker disabled (deprecated upstream, absent on s390x)"

patches/pkgbuild/gcc.sh

@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+# gcc: keep only the front ends that bootstrap without an existing compiler
+# of the same language.
+#
+#   configure: error: GNAT is required to build ada
+#   configure: error: GDC is required to build d
+#
+# Ada and D are written in themselves: building their front ends needs an
+# existing Ada or D compiler of a compatible vintage. Ubuntu ships gnat, but
+# not one GCC 15 accepts, and D has no bootstrap compiler here at all.
+# Modula-2 and COBOL have the same shape of problem.
+#
+# Nothing in a core bootstrap -- and nothing in ERPLibre -- is written in any
+# of them. C, C++, Fortran, LTO and the Objective-C front ends cover
+# everything the rest of this port compiles.
+#
+# STAGE 1 CONCESSION, not a permanent one. Once the port is self-hosting its
+# own gcc can bootstrap the others, and this hook should be revisited.
+set -euo pipefail
+sed -i 's/^\(\s*--enable-languages=\).*\\$/\1c,c++,fortran,lto,objc,obj-c++ \\/' PKGBUILD
+grep -m1 -- '--enable-languages' PKGBUILD
+grep -qE 'enable-languages=[^ ]*(ada|,d,|m2|cobol)' PKGBUILD && {
+    echo "gcc: a self-hosted front end is still enabled" >&2; exit 1; }
+echo "gcc: front ends reduced to those that bootstrap from C"

patches/pkgbuild/libtool.sh

@@ -0,0 +1,30 @@
+#!/usr/bin/env bash
+# libtool: drop the 32-bit multilib split package.
+#
+# Arch builds libtool as (libtool lib32-libltdl). The build() step that
+# compiles the 32-bit half is already guarded by [[ $CARCH = x86_64 ]] and
+# never runs here -- but prepare() copies the source tree to src/libtool32
+# UNCONDITIONALLY, and package_lib32-libltdl() then packages a tree that was
+# never built:
+#
+#   cp: cannot create regular file '.../src/libtool32/libtool/.git...'
+#
+# lib32 is i686-on-x86_64 multilib. It has no meaning on s390x, where no
+# 32-bit userspace is shipped and lib32-glibc does not exist. Removed rather
+# than repaired: the artefact itself is architecture-specific.
+set -euo pipefail
+sed -i 's/^pkgname=(libtool lib32-libltdl)$/pkgname=(libtool)/' PKGBUILD
+sed -i '/lib32-gcc-libs/d; /lib32-glibc/d; /libtool32/d' PKGBUILD
+python3 - <<'PY'
+import io, re
+s = io.open("PKGBUILD", encoding="utf-8").read()
+s = re.sub(r"\npackage_lib32-libltdl\(\)\s*\{.*?\n\}\n", "\n", s, flags=re.S)
+io.open("PKGBUILD", "w", encoding="utf-8").write(s)
+PY
+# Verify what actually matters. "lib32" also appears in a harmless
+# lt_cv_sys_lib_dlsearch_path_spec string and in the CARCH-guarded block;
+# grepping for the bare word declared a false failure.
+grep -q '^pkgname=(libtool)$' PKGBUILD || { echo "libtool: pkgname not reduced" >&2; exit 1; }
+grep -q 'package_lib32-libltdl' PKGBUILD && { echo "libtool: lib32 package function remains" >&2; exit 1; }
+grep -q 'libtool32' PKGBUILD && { echo "libtool: libtool32 tree still referenced" >&2; exit 1; }
+echo "libtool: lib32 split package removed (x86-only multilib)"