SCons: Explicitly enable -mfpmath=sse -mstackrealign for x86_32

Passing `-msse2` doesn't seem to be sufficient to opt into SSE floating point math
instead of the less stable x87.

`-mstackrealign` also seems necessary when using SSE on x86_32.

modules/raycast/SCsub

@@ -71,7 +71,6 @@ if env["builtin_embree"]:
             env.Append(LINKFLAGS=["psapi.lib"])
         else:
             env.Append(LIBS=["psapi"])
-            env_raycast.Append(CCFLAGS=["-mstackrealign"])
 
     if env.msvc:  # Disable bogus warning about intentional struct padding.
         env_raycast.Append(CCFLAGS=["/wd4324"])