Bug #:

Submitted by:
Reviewed by:
Lot's of changes related to type checking binary expressions.
- Changed the name/proto of ImplicitConversion. It is now named UsualUnaryConversion - it takes a
type and returns a type. This allowed me to remove the explicit node creation for array/function->pointer conversions.
- Added function UsualArithmeticConversions().
- Changed all the "Check" functions for binary ops. They use the new "Usual" functions above.
- new predicates on Type, isSignedIntegerType()/isUnsignedIntegerType().
- moved getDecl() out of the Sema class. It is now a static helper function in SemaExpr.cpp. It was also renamed getPrimaryDeclaration().
- Added CheckArithmeticOperand() for consistency with the other unary "Check" functions.

Should finish up the binary expressions tomorrow...with a small number of "FIXME's"

llvm-svn: 39411