[PowerPC]To provide better compatibility with gcc I added the __bool keyword...

[PowerPC]To provide better compatibility with gcc I added the __bool keyword to the Alitivec support in clang. __bool is functionally identical to using bool when declaring vector types. For example:

vector bool char v_bc;
vector __bool char v___bc;

clang already supported vector/__vector and pixel/__pixel but was missing __bool.

http://llvm.org/bugs/show_bug.cgi?id=19220

For reference: https://gcc.gnu.org/onlinedocs/gcc-4.9.2/gcc/PowerPC-AltiVec_002fVSX-Built-in-Functions.html

http://reviews.llvm.org/D6882

llvm-svn: 225664