Fix some tests for up to 64-wide gangs

tests/test-60.ispc

@@ -4,12 +4,12 @@ export uniform int width() { return programCount; }
 
 export void f_fu(uniform float RET[], uniform float aFOO[], uniform float b) {
     float a = aFOO[programIndex];
-    while (a < 20)
+    while (a < 64)
         ++a;
     RET[programIndex] = a;
 }
 
 
 export void result(uniform float RET[]) {
-    RET[programIndex] = 20;
+    RET[programIndex] = 64;
 }