[analyzer] operator new: Fix path diagnostics around the operator call.

Implements finding appropriate source locations for intermediate diagnostic
pieces in path-sensitive bug reports that need to descend into an inlined
operator new() call that was called via new-expression. The diagnostics have
worked correctly when operator new() was called "directly".

Differential Revision: https://reviews.llvm.org/D41409
rdar://problem/12180598

llvm-svn: 322791