We shouldn't need to pass -fno-strict-aliasing when building clang with clang.

Summary: The code comments in the Makefile indicate this was put in place to support issues when building clang with GCC. Today clang's strict aliasing works, so we shouldn't pass -fno-strict-aliasing when building with clang.

Reviewers: bogner, echristo

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D12036

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@245304 91177308-0d34-0410-b5e6-96231b3b80d8