Minor bug fixes and cleanup

Minor bug fixes and cleanup

- Removed unused variables
- Fixed member initialization order in a few classes
- Fixed Surface::setSwapBehavior()
- Removed unused mPixelPackingStateDirty members
- Fixed initialization of "size" member in LinkedVarying class
- Fixed constness of a string
- Removed unused static functions
- Added parenthesis to fix && / || order ambiguity

Change-Id: Ia9ad8eaca335c60871fdc58037e441aa2010a641
Reviewed-on: https://swiftshader-review.googlesource.com/4301
Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>