[Sema] When checking if a bitcast is appropriate between vector types, take into
consideration the num-of-elements*width-of-element width.

Disallow casts when such width is not equal between the vector types otherwise
we may end up with an invalid LLVM bitcast.

rdar://15722308.

llvm-svn: 198474
GitOrigin-RevId: eb68f6a9de3c782e93321e48422b4ac2b4f9a6be
2 files changed