Bug #:

Submitted by:
Reviewed by:
- Unified CheckSimpleAssignmentOperands/CheckCompoundAssignmentOperands
into one function, named CheckAssignmentOperands. One less function to maintain.
- Converted the unary check functions (ParseUnaryOp and friends) to have
the same API as their binary counterparts.
- Implemented CheckIndirectionOperand (was stubbed). While testing, noticed
that Expr::isModifiableLvalue was incomplete (fixed and referenced draft).
- Added constantOne instance variable to Sema.
- Removed CheckArithmeticOperand (the code was so simple that it is now
part of ParseUnaryOp). The name wasn't great anyway:-)

llvm-svn: 39435