Support GL_ARB_fragment_shader_interlock

Test/spv.fsi.frag

@@ -0,0 +1,20 @@
+#version 450
+#extension GL_ARB_fragment_shader_interlock : enable
+
+layout(set = 0, binding = 0) coherent buffer B1 {
+    layout(offset = 0)  int x;
+} b1;
+
+layout(set = 0, binding = 1, rgba32f) coherent uniform image2D im;
+
+layout(sample_interlock_ordered) in;
+
+void main() {
+
+    beginInvocationInterlockARB();
+
+    b1.x = 1;
+    imageStore(im, ivec2(0,0), vec4(0));
+
+    endInvocationInterlockARB();
+}