Improved false positive rate for the idempotent operations checker and moved...

Improved false positive rate for the idempotent operations checker and moved it into the default path-sensitive analysis options.
- Added checks for static local variables, self assigned parameters, and truncating/extending self assignments
- Removed command line option (now default with --analyze)
- Updated test cases to pass with idempotent operation warnings

llvm-svn: 108550