mesa: replace _mesa_problem() with assert() in hash table

There should be no way the OpenGL test suites don't hit the assert()
should we do something to cause this code path to be taken.

Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>

src/mesa/main/hash.c

@@ -339,12 +339,10 @@ _mesa_HashRemove_unlocked(struct _mesa_HashTable *table, GLuint key)
    assert(table);
    assert(key);
 
-   /* have to check this outside of mutex lock */
-   if (table->InDeleteAll) {
-      _mesa_problem(NULL, "_mesa_HashRemove illegally called from "
-                    "_mesa_HashDeleteAll callback function");
-      return;
-   }
+   /* assert if _mesa_HashRemove illegally called from _mesa_HashDeleteAll
+    * callback function. Have to check this outside of mutex lock.
+    */
+   assert(!table->InDeleteAll);
 
    if (key == DELETED_KEY_VALUE) {
       table->deleted_key_data = NULL;