[analyzer] When checking Foundation method calls, match the selectors exactly.

This also includes some infrastructure to make it easier to build multi-argument
selectors, rather than trying to use string matching on each piece. There's a bit
more setup code, but less cost at runtime.

PR18908

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@205827 91177308-0d34-0410-b5e6-96231b3b80d8