scons: Remove dead code/comments.

- Remove no-op if-clause.

- -mstackrealign has been enabled again on MinGW for quite some time and
  appears to work alright nowadays.

- Drop -mmmx option as it is implied my -msse, and we don't use MMX
  intrinsics anyway.

Reviewed-by: Brian Paul <brianp@vmware.com>
Reviewed-by: Roland Scheidegger <sroland@vmware.com>
1 file changed