Add: 32bpp SSE2 blitter palette animator (#6795)

Create a new blitter mode: 32bpp-sse2-anim, which is 32bpp-anim + this.
32bpp-sse2-anim is now used by default where 32bpp-anim would have been.
Also use this with the 32bpp-sse4-anim blitter.

See issue #6469.

source.list

@@ -913,6 +913,8 @@ script/api/script_window.cpp
 blitter/32bpp_anim.cpp
 blitter/32bpp_anim.hpp
 #if SSE
+blitter/32bpp_anim_sse2.cpp
+blitter/32bpp_anim_sse2.hpp
 blitter/32bpp_anim_sse4.cpp
 blitter/32bpp_anim_sse4.hpp
 #end