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

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

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@108550 91177308-0d34-0410-b5e6-96231b3b80d8