Rename LLVMContext diagnostic handler types and functions.

Rename LLVMContext diagnostic handler types and functions.

These are now generally used for all diagnostics from the backend, not just
for inline assembly, so this drops the "InlineAsm" from the names.  No
functional change.  (I've left aliases for the old names but only for long
enough to let me switch over clang to use the new ones.)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171047 91177308-0d34-0410-b5e6-96231b3b80d8