changing uniform_min and uniform_max implementations for avx targets

tests/max-double-1.ispc

@@ -0,0 +1,19 @@
+
+export uniform int width() { return programCount; }
+
+
+
+export void f_du(uniform float RET[], uniform double aFOO[], uniform double b) {
+    double a = aFOO[programIndex];
+    RET[programIndex] = max(3 * a, (double)10.f);
+    RET[width()-1] = max(b, (double)100);
+}
+
+
+export void result(uniform float RET[]) {
+    RET[programIndex] = 3 * (1+programIndex);
+    RET[0] = 10;
+    RET[1] = 10;
+    RET[2] = 10;
+    RET[programCount-1] = 100;
+}