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



git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@209752 91177308-0d34-0410-b5e6-96231b3b80d8