SPV 1.4: Emit SignExtend and ZeroExtend for integer image reads/writes.

Test/spv.1.4.texture.frag

@@ -0,0 +1,26 @@
+#version 450
+
+uniform  sampler2D       texSampler2D;
+uniform isampler2D      itexSampler2D;
+uniform usampler2D      utexSampler2D;
+
+in  vec2 t;
+in  vec2 coords2D;
+flat in ivec2 iCoords2D;
+
+out vec4 color;
+
+flat in int iLod;
+
+void main()
+{
+    vec4  color = vec4(0.0, 0.0, 0.0, 0.0);
+
+    color += texture( texSampler2D, coords2D);
+    color += texture(itexSampler2D, coords2D);
+    color += texture(utexSampler2D, coords2D);
+
+    color += texelFetch( texSampler2D, iCoords2D, iLod);
+    color += texelFetch(itexSampler2D, iCoords2D, iLod);
+    color += texelFetch(utexSampler2D, iCoords2D, iLod);
+}