[Patch] Add and use new RTL predicates for i386 target

[Paolo Bonzini]

I must say I don't see the point of extra RTL predicates, but I'll let 
others judge.  MEM and REG should be everything that's needed IMHO.

Anyway,

+  if (!(X87_FLOAT_MODE_P (mode) && (CONST_DOUBLE_P (x))))

Extra parentheses.

Paolo