Subzero: Run sandboxed cross tests, and do some cleanup.

crosstest/test_arith_frem.ll

-target triple = "i686-pc-linux-gnu"
-
 define float @_Z6myFremff(float %a, float %b) {
   %rem = frem float %a, %b
   ret float %rem
 }
 
 define double @_Z6myFremdd(double %a, double %b) {
   %rem = frem double %a, %b
   ret double %rem
 }
 
 define <4 x float> @_Z6myFremDv4_fS_(<4 x float> %a, <4 x float> %b) {
   %rem = frem <4 x float> %a, %b
   ret <4 x float> %rem
 }