Add EXTWARN Diagnostic class.
 - Like EXTENSION but always generates a warning (even without
   -pedantic).
 - Updated ptr -> int, int -> ptr, and incompatible cast warnings to
   be EXTWARN.
 - Other EXTENSION level diagnostics should be audited for upgrade.
 - Updated several test cases to fix code which produced unanticipated
   warnings.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@54335 91177308-0d34-0410-b5e6-96231b3b80d8
6 files changed