When disabling SSE, make sure -fpmath is not set to use SSE either

This fixes errors when we inject sse options through CFLAGS and now
that we have -Werror turned on by default this warning turns into an
error on x86:

$ gcc -m32 -march=core2 -mtune=core2 -msse3 -mfpmath=sse -x c /dev/null -S -mno-sse -mno-mmx
/dev/null:1:0: warning: SSE instruction set disabled, using 387 arithmetics

Where as:

$ gcc -m32 -march=core2 -mtune=core2 -msse3 -mfpmath=sse -x c /dev/null -S -mno-sse -mno-mmx -mfpmath=387

Generates no warnings.