[libclang] Don't set dylib load address to 0xe000000.

Per Greg Clayton:
libclang.dylib is trying to be smart and load itself at a valid address
to be able to load faster which would work for 32 bit systems,
bit won't make any difference on 64 bit systems.
It should either pick a better 64 bit address, or just let itself be loaded at zero.

rdar://11159142

llvm-svn: 155246