Cleanup: Remove data duplication from SMAA lookup tables

These 2 large tables, `areaTexBytes` and `searchTexBytes`, contributed
~176kb worth of duplicate data into the `blender` executable due to the
header being used in multiple places. We were lucky that only 2
translation units had included this header so only 1 duplicate copy of
each was wasted.

Define the tables as `extern` to address this.

Reviewed By: fclem

Differential Revision: https://developer.blender.org/D12723

source/blender/draw/CMakeLists.txt

@@ -108,6 +108,7 @@ set(SRC
   intern/draw_select_buffer.c
   intern/draw_texture_pool.cc
   intern/draw_shader.c
+  intern/smaa_textures.c
   intern/draw_view.c
   engines/basic/basic_engine.c
   engines/image/image_engine.c