dmabuf: Make a define for the version of the dmabuf attribute struct

I should've done this in the first place, and the version checks are
starting to spread out a bit.

src/modules/evas/engines/gl_drm/evas_engine.c

@@ -1320,7 +1320,7 @@ eng_image_native_set(void *engine, void *image, void *native)
              struct dmabuf_attributes *a;
 
              a = ns->data.wl_dmabuf.attr;
-             if (a->version != 1)
+             if (a->version != EVAS_DMABUF_ATTRIBUTE_VERSION)
                {
                   glsym_evas_gl_common_image_free(img);
                   return NULL;

src/modules/evas/engines/software_generic/evas_native_common.h

@@ -29,6 +29,8 @@
 
 //#include <Evas_Common.h>
 
+#define EVAS_DMABUF_ATTRIBUTE_VERSION 1
+
 struct dmabuf_attributes
 {
   /* This must exactly match the struct in Enlightenment.

src/modules/evas/engines/software_generic/evas_native_dmabuf.c

@@ -107,7 +107,7 @@ _evas_native_dmabuf_surface_image_set(void *image, void *native)
         if (!n) return NULL;
 
         a = ns->data.wl_dmabuf.attr;
-        if (a->version != 1)
+        if (a->version != EVAS_DMABUF_ATTRIBUTE_VERSION)
           {
              free(n);
              return NULL;