BUILD_SHARED_LIBS build llvm component as shared library,
which can reduce the size a lot.
Normally, the binary use ORIGIN../lib to load component libraries,
unfortunatly, ORIGIN is not supported by AIX ld.
We hardcoded the build lib and install lib path in rpath for now
to enable BUILD_SHARED_LIBS build.
Understand that this is not perfect solution,
we can update this when we find better solution.