Fixed some warnings

Fixed some warnings

- Changing "char*" to "const char*" when a
  function can receive string literals
- Removed some unused variables and members
- Fixed some signed vs unsigned comparisons
- Added braces for safety on code like:
  if(...) if(...) ... else ...
  to make it:
  if(...) { if(...) ... else ... }
  otherwise the else is ambiguous
- Reordered some member initializations to
  fit the declaration order in the class
- OutDir must end with a backslash in VS

Change-Id: I903bd7afac882090841da0c0f4ebb30db0a5dd37
Reviewed-on: https://swiftshader-review.googlesource.com/3501
Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>