changing uniform_min and uniform_max implementations for avx targets

tests/max-double-2.ispc

@@ -0,0 +1,18 @@
+
+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(-10 * (a-3), (double).1f);
+    RET[width() - 1] = max(-10 * b, (double)2);
+}
+
+export void result(uniform float RET[]) {
+    RET[programIndex] = .1;
+    RET[0] = 20;
+    RET[1] = 10;
+    RET[programCount - 1] = 2;
+}
+