Fix #131095: EEVEE: Support long property path as attribute name

Attribute name could be a path built from multiple object/property names
while each of them can be 64 symbols long.
This was fixed by cff53fdb53, so Cycles
can handle this. But eevee need additional change.

Pull Request: https://projects.blender.org/blender/blender/pulls/131183

source/blender/gpu/GPU_material.hh

@@ -400,7 +400,7 @@ struct GPULayerAttr {
   GPULayerAttr *next, *prev;
 
   /* Meaningful part of the attribute set key. */
-  char name[68]; /* MAX_CUSTOMDATA_LAYER_NAME */
+  char name[256]; /* Multiple MAX_CUSTOMDATA_LAYER_NAME */
   /** Hash of name[68]. */
   uint32_t hash_code;