Cleanup: Missing include

This included is needed for the `ATTR_NONNULL` macro used in the header.
As found in a recent c --> c++ if the includes get ordered in a different order
this could result in an error.

Re commits rBc20098e6ec6adee874a12e510aa4a56d89f92838

source/blender/render/RE_texture.h

@@ -22,6 +22,8 @@
 
 #pragma once
 
+#include "BLI_compiler_attrs.h"
+
 /* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */
 /* this include is for non-render pipeline exports (still old cruft here) */
 /* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */