Cmake build changes.

Disables exception handling in LLDB, using appropriate compiler
flags depending on the platform. This is consistent with the build
of LLVM, should improve performance, and also removes a substantial number
of warnings from the Windows build.

See http://reviews.llvm.org/D3929 for more details.

Change by Zachary Turner

llvm-svn: 209752
GitOrigin-RevId: b6ee2f8061517ee1fbed20ac8b8c920d3d76f62f