CMake: Set WEBP_BUILD_GIF2WEBP to off
CMake: Set WEBP_BUILD_GIF2WEBP to off

Instead of unsetting WEBP_BUILD_GIF2WEBP,
disable it to keep it displayed in ccmake.
Disable WEBP_BUILD_GIF2WEBP before it's tested.
Do the same for WEBP_BUILD_ANIM_UTILS.

Change-Id: I91920814fbda4825ced9a801bb005f8d44bfe09c

webmproject/libwebp,webmproject/libwebp,PKRoma/libwebp,webmproject/libwebp,PKRoma/libwebp,PKRoma/libwebp,PKRoma/libwebp,PKRoma/libwebp,webmproject/libwebp,PKRoma/libwebp,webmproject/libwebp