[analyzer] MallocChecker should not do post-call checks on inlined functions.

If someone provides their own function called 'strdup', or 'reallocf', or
even 'malloc', and we inlined it, the inlining should have given us all the
malloc-related information we need. If we then try to attach new information
to the return value, we could end up with spurious warnings.

<rdar://problem/12317671>

llvm-svn: 164276