mesa/main: replace Elements() with ARRAY_SIZE()

We've been using a mix of these two macros for a while now.  Let's
just use the later everywhere.  It seems to be the convention used
by other open-source projects.

Acked-by: Ilia Mirkin <imirkin@alum.mit.edu>

src/mesa/main/shared.c

@@ -105,7 +105,7 @@ _mesa_alloc_shared_state(struct gl_context *ctx)
          GL_TEXTURE_2D,
          GL_TEXTURE_1D
       };
-      STATIC_ASSERT(Elements(targets) == NUM_TEXTURE_TARGETS);
+      STATIC_ASSERT(ARRAY_SIZE(targets) == NUM_TEXTURE_TARGETS);
       shared->DefaultTex[i] = ctx->Driver.NewTextureObject(ctx, 0, targets[i]);
    }