Fix a build issue where LLVM_LDFLAGS contains newlines.

On my system. llvm_set returns a variable that contains newlines, which breaks the build. This fix makes sure that they are removed before setting LLVM_LDFLAGS for the last time.

Environment: 

Linux kartofel 3.13.0-24-generic #46-Ubuntu SMP Thu Apr 10 19:11:08 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
cmake version 2.8.12.2
llvm version 3.5