[X86] LowerVectorAllEqual - split ALLOF(CMPEQ(X,Y)) ->...

[X86] LowerVectorAllEqual - split ALLOF(CMPEQ(X,Y)) -> AND(CMPEQ(X[0],Y[0]),CMPEQ(X[1],Y[1]),....) on MOVMSK codegen

Fix minor regression on pre-PTEST targets, since these are always 128-bits we're better off reducing the comparison results (assuming we're not comparing against 0/-1).