configure.ac: Link mcdisassembler component.
configure.ac: Link mcdisassembler component.

gallivm now depends on it. And depending on particular LLVM version /
configure options, the build can fail without this change due to
undefined reference to `LLVM*Disasm*' symbols.

Trivial.

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler