[clang][analyzer] Improve BlockInCriticalSectionsChecker with multi-section and recursive mutex support

* Add support for multiple, potentially overlapping critical sections:
  The checker can now simultaneously handle several mutex's critical
  sections without confusing them.
* Implement the handling of recursive mutexes:
  By identifying the lock events, recursive mutexes are now supported.
  A lock event is a pair of a lock expression and the SVal of the mutex
  that it locks, so even multiple locks of the same mutex (and even by
  the same expression) is now supported.
* Refine the note tags generated by the checker:
  The note tags now correctly show just for mutexes those are
  active at point of error, and multiple acqisitions of the same mutex
  are also noted.

Author: gamesh411