Pass -target instead of using "REQUIRES: clang-driver".

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@189822 91177308-0d34-0410-b5e6-96231b3b80d8
Attempt to migrate default dwarf version to 4 for linux.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@189823 91177308-0d34-0410-b5e6-96231b3b80d8