gl-renderer: Use ARRAY_COPY for buffer state

We've got a nice shiny ARRAY_COPY macro, so use it rather than memcpy or
hand-unrolled assignments.

Signed-off-by: Daniel Stone <daniels@collabora.com>

libweston/renderer-gl/gl-renderer.c

@@ -2096,12 +2096,10 @@ unsupported:
 
 	gb->pitch = pitch;
 	gb->shader_variant = shader_variant;
-	memcpy(gb->offset, offset, sizeof(offset));
+	ARRAY_COPY(gb->offset, offset);
-	memcpy(gb->hsub, hsub, sizeof(hsub));
+	ARRAY_COPY(gb->hsub, hsub);
-	memcpy(gb->vsub, vsub, sizeof(vsub));
+	ARRAY_COPY(gb->vsub, vsub);
-	gb->gl_format[0] = gl_format[0];
+	ARRAY_COPY(gb->gl_format, gl_format);
-	gb->gl_format[1] = gl_format[1];
-	gb->gl_format[2] = gl_format[2];
 	gb->gl_pixel_type = gl_pixel_type;
 	gb->needs_full_upload = true;