Doh, fix behaviour change introduced in r176168 which is tested in clang,
not llvm.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176172 91177308-0d34-0410-b5e6-96231b3b80d8
In GCC 4.7, function names are now forbidden from .gcda files. Support this by
passing a null pointer to the function name in to GCDAProfiling, and add another
switch onto GCOVProfiling.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176173 91177308-0d34-0410-b5e6-96231b3b80d8