[CMake] Add missing set_output_directory after Takumi's change in r198205.

Plugins need to go in build/Debug/lib as well (rather than build/lib/Debug).

Also, fix the SHLIBDIR path for Xcode, which by default includes Xcode build
settings rather than a simple %(build_mode)s parameter.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198344 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed