Split Linux-specific and OS X specific stuff. Add include_directories

Only add the -std=c++11 flag when needed, don't touch current flags.

git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@179821 91177308-0d34-0410-b5e6-96231b3b80d8
Remove an unneeded local var, a missing return statement in kernel search code, thanks to Greg Clayton for finding these.


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@179822 91177308-0d34-0410-b5e6-96231b3b80d8