This patch makes the behavior of clang consistent with the behavior of gcc 4.6...

This patch makes the behavior of clang consistent with the behavior of gcc 4.6 in cases where both -fPIC and -fPIE is used.

- Separately check if -fPIE was specified in the command line and define both __PIC__ and __PIE__ when -fPIE is used. We need to check this separately because -fPIE will infer -fPIC even if its not explicitly used.
- Fixed existing tests.
- Added new tests for cases where both -fPIC and -fPIE is used.

Author: Tareq A. Siraj <tareq.a.siraj@intel.com>
Fixes: PR13221
Review: http://llvm-reviews.chandlerc.com/D94
llvm-svn: 167846