Travis-CI: do not test gold linkers with clang

clang does not know -fuse-ld=gold. It only needs -flto, which
automatically adds -plugin=LLVMgold.so to the linker command line, but
this does not work on Travis-CI because the gold linker plugin is not
installed:

    /usr/bin/ld: /usr/local/clang-3.9.0/bin/../lib/LLVMgold.so: error
    loading plugin: /usr/local/clang-3.9.0/bin/../lib/LLVMgold.so:
    cannot open shared object file: No such file or directory

Disable in the build matrix the combination of linking with special
linkers with using clang.

Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>
1 file changed