mesa/teximage: add _mesa_is_cube_map_texture utility method

Reviewed-by: Dave Airlie <airlied@redhat.com>
diff --git a/src/mesa/main/teximage.c b/src/mesa/main/teximage.c
index 78d5b55..616a929 100644
--- a/src/mesa/main/teximage.c
+++ b/src/mesa/main/teximage.c
@@ -242,6 +242,24 @@
    };
 }
 
+/**
+ * Test if a target is a cube map.
+ *
+ * \param target texture target.
+ *
+ * \return true if the target is a cube map, false otherwise.
+ */
+bool
+_mesa_is_cube_map_texture(GLenum target)
+{
+   switch(target) {
+   case GL_TEXTURE_CUBE_MAP:
+   case GL_TEXTURE_CUBE_MAP_ARRAY:
+      return true;
+   default:
+      return false;
+   }
+}
 
 /**
  * Return the proxy target which corresponds to the given texture target
diff --git a/src/mesa/main/teximage.h b/src/mesa/main/teximage.h
index 5a29c6c..8b68706 100644
--- a/src/mesa/main/teximage.h
+++ b/src/mesa/main/teximage.h
@@ -256,6 +256,10 @@
                            struct gl_buffer_object *bufObj,
                            GLintptr offset, GLsizeiptr size,
                            const char *caller);
+
+bool
+_mesa_is_cube_map_texture(GLenum target);
+
 /*@}*/