This commit removes the hardcoded dependency in the libunbound
pkg-config .pc file on the libcrypto and libssl modules and instead
populates the .pc file based on which crypto library was selected at
configure time.
Note that the .pc file specifies pkg-config module names for the
"Requires" line and this can vary from the library filename (e.g. "nss"
is the pkg-config module name vs. "nss3" being the library name).
According to the pkg-config manpage, the "Libs" line in a .pc file
should give the link flags "specific to your package", and specifically
says not to include link flags for dependencies:
Libs: This line should give the link flags specific to your
package. Don't add any flags for required packages;
pkg-config will add those automatically.
Add a new configure option `--with-libbsd', which allows to use libbsd's
portable implementations of:
strlcpy strlcat arc4random arc4random_uniform reallocarray
instead of the embedded code copies in contrib/, which will be
difficult to maintain in the long term.
Also patch util/random.c so that, when building with libbsd and without
OpenSSL, arc4random can still be used as the PRNG. Otherwise, building
with libnettle would need a kernel-specific getentropy implementation,
and libbsd does not export one.
[edmonds@debian.org: Imported patch description from BTS, refreshed
patch against Unbound 1.9.6.]
