havelib: improve bi-arch support

[Bruno Haible]

This series of patches improves the bi-arch support in the AC_LIB_LINKFLAGS
macro.

Two situations are now supported that were not supported before:

  * A distro might store 64-bit libs in $PREFIX/lib and 32-bit libs in
    $PREFIX/lib32. This is how it is e.g. in Manjaro Linux. Until a couple
    of years ago, virtually all distros were using the opposite situation:
    64-bit libs in $PREFIX/lib64 and 32-bit libs in $PREFIX/lib.

  * A library may be installed in $PREFIX/lib64 or $PREFIX/lib32 AND,
    in the opposite bitness, in $PREFIX/lib. The macro will now pick the
    library from the right directory, depending on whether $CC is compiling
    for 32-bit or for 64-bit.


2019-11-17  Bruno Haible  <address@hidden>

        havelib: Remove redundant code.
        * m4/lib-prefix.m4 (AC_LIB_PREPARE_MULTILIB): Remove Solaris specific
        test for 64-bit host. Use gl_HOST_CPU_C_ABI_32BIT result instead.

        host-cpu-c-abi: Add support for unknown CPUs.
        * m4/host-cpu-c-abi.m4 (gl_HOST_CPU_C_ABI_32BIT): Set
        gl_cv_host_cpu_c_abi_32bit to 'unknown' if we don't know whether it's
        32-bit or 64-bit.

        havelib: Match the bitness when searching for libraries.
        * m4/lib-prefix.m4 (AC_LIB_PREPARE_MULTILIB): Define a function
        acl_is_expected_elfclass.
        * m4/lib-link.m4 (AC_LIB_LINKFLAGS_BODY): When testing whether a library
        file exists, in ELF, also test whether it has the ELF class that
        corresponds to the host's bitness.

        havelib: Make libdirstems processing more flexible.
        * m4/lib-prefix.m4 (AC_LIB_PREPARE_MULTILIB): Set 3 libdirstem
        variables: Consider 'lib' always, also on Solaris. Look for lib32 in
        addition to lib64. Don't invoke /usr/bin/gcc (reverting the second
        patch from 2017-02-19).
        * m4/lib-link.m4 (AC_LIB_LINKFLAGS_BODY): Consider up to 3 additional
        libdirs, even when the first one exists as a directory.

0001-havelib-Remove-redundant-code.patch
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0002-host-cpu-c-abi-Add-support-for-unknown-CPUs.patch
Description: Text Data

0003-havelib-Match-the-bitness-when-searching-for-librari.patch
Description: Text Data

0004-havelib-Make-libdirstems-processing-more-flexible.patch
Description: Text Data