Change CROSS_TARGETS to CROSS_FORMATS because that makes more sense.

Check if already cross-compiling and only build the cross-tools if
not cross-compiling (to save time).

gnu/usr.bin/binutils/as/Makefile

@@ -5,11 +5,31 @@
 .include "${.CURDIR}/../Makefile.inc0"
 
 GASES=		${BINUTIL_ARCH}
-GASES+=		${CROSS_TOOLS} ${CROSS_TARGETS}	
+
+# Only build the cross tools when not cross-compiling.
+__MA!=/sbin/sysctl -b hw.machine_arch
+__M!=/sbin/sysctl -b hw.machine
+.if ${__MA} == ${MACHINE_ARCH} || ${__M} == ${MACHINE}
+.if defined(CROSS_ARCH)
+.for _g in ${CROSS_ARCH}
+.if (${GASES:R:M${_g:R}} == "")
+GASES+=$(_g)
+.endif
+.endfor
+.endif
+.endif
+
 .for _g in ${GASES}
 .if exists(${.CURDIR}/as_${_g})
 SUBDIR+=	as_${_g}
 .endif
+.if defined(CROSS_FORMATS)
+.for _f in ${CROSS_FORMATS}
+.if exists(${.CURDIR}/${_g}-${_f})
+SUBDIR+=	${_g}-${_f}
+.endif
+.endfor
+.endif
 .endfor
 
 .include <bsd.subdir.mk>