Fix compiler warnings for VS2010 /W4 in intra.c.
Fix compiler warnings for VS2010 /W4 in intra.c.

- Working towards issue #11.

lu-zero/kvazaar,ultravideo/kvazaar,lu-zero/kvazaar,ultravideo/kvazaar,ultravideo/kvazaar,ultravideo/kvazaar,lu-zero/kvazaar,lu-zero/kvazaar,ultravideo/kvazaar