Ignore line numbers on debug intrinsics. Add an assert to ensure that we aren't emitt...

Ignore line numbers on debug intrinsics. Add an assert to ensure that we aren't emitting line number zero, the .gcno format uses this to indicate that the next field is a filename.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210068 91177308-0d34-0410-b5e6-96231b3b80d8