Bug #:

Submitted by:
Reviewed by:
- Added Sema::isConstantArrayType() and Type::isConstantSizeType().
- Implemented type checking for "variably modified" types (i.e. VLA's).
Added checking for file scope variables, static variables, member variables,
and typedefs.
- Changed Expr::isIntegerConstantExpr() to non-virtual implementation.
Fixed bug with sizeof/alignof. Looking at the diff, I may need to
add a check to exclude alignof.
- Added Expr::isConstantExpr()...non-virtual, like above.
- Added typechecking for case statements (found a bug with actions/parsing...).
- Added several diagnostics.
- Fixed several comments.
Started implemented constant expression checking for arrays.

llvm-svn: 39437