Bug #:

Submitted by:
Reviewed by:
- Enhanced UsualAssignmentConversions() to properly handle type qualifiers on
pointers.
- Added helper function Sema::pointerTypeQualifiersAlign().
- Noticed several errors improperly named "ext_" (fixed).
- Combined structureTypesAreCompatible/unionTypesAreCompatible into
tagTypesAreCompatible.
- Renamed Type::getCanonicalType() to Type::getCanonicalTypeInternal(). It
will never confuse/bite me again:-)
- Added a couple extension diagnostics for discarded type qualifiers.

llvm-svn: 39439