[analyzer] Don't process autorelease counts in synthesized function bodies.

We process autorelease counts when we exit functions, but if there's an
issue in a synthesized body the report will get dropped. Just skip the
processing for now and let it get handled when the caller gets around to
processing autoreleases.

(This is still suboptimal: objects autoreleased in the caller context
should never be warned about when exiting a callee context, synthesized
or not.)

Second half of <rdar://problem/14611722>

llvm-svn: 187625