[analyzer] Suppress false positives in std::shared_ptr

The analyzer does not model C++ temporary destructors completely and so
reports false alarms about leaks of memory allocated by the internals of
shared_ptr:

  std::shared_ptr<int> p(new int(1));
  p = nullptr; // 'Potential leak of memory pointed to by field __cntrl_'

This patch suppresses all diagnostics where the end of the path is inside
a method in std::shared_ptr.

It also reorganizes the tests for suppressions in the C++ standard library
to use a separate simulated header for library functions with bugs
that were deliberately inserted to test suppression. This will prevent
other tests from using these as models.

rdar://problem/23652766

llvm-svn: 274691