PR32042: Create inlined debug info for EmitInlinedInheritingCXXConstructorCall.

When clang emits an inheriting C++ constructor it may inline code
during the CodeGen phase. This patch ensures that any debug info in
this inlined code gets a proper inlined location. Otherwise we can end
up with invalid debug info metadata, since all inlined local variables
and function arguments would be reparented into the call site.

Analogous to ApplyInlineLocation this patch introduces a
ApplyInlineDebugLocation scoped helper to facilitate entering an
inlined scope and cleaning up afterwards.

This fixes one of the issues discovered in PR32042.

rdar://problem/30679307

llvm-svn: 296388