Add test shader for coherent SSBO.

reference/shaders/comp/coherent-block.comp

@@ -0,0 +1,13 @@
+#version 310 es
+layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;
+
+layout(binding = 1, std430) coherent restrict writeonly buffer SSBO
+{
+    vec4 value;
+} _10;
+
+void main()
+{
+    _10.value = vec4(20.0);
+}
+

shaders/comp/coherent-block.comp

@@ -0,0 +1,12 @@
+#version 310 es
+layout(local_size_x = 1) in;
+
+layout(binding = 1) coherent restrict writeonly buffer SSBO
+{
+	vec4 value;	
+};
+
+void main()
+{
+	value = vec4(20.0);
+}