Allow mongoc_init() to not use our mm

There is a shutdown race condition in the mongoc counters segment
allocation where zend mm will free the counters during RSHUTDOWN.
This happens as there is no "persistent alloc" callback from the bson
allocators that we can pemalloc() for.
Instead, we'll let mongoc_init use its own alloctors -- but we have to
remember to reset the alloc callbacks before mongoc_cleanup()

Author: bjori

php_phongo.c

@@ -1674,10 +1674,10 @@ PHP_MINIT_FUNCTION(mongodb)
 
 	REGISTER_INI_ENTRIES();
 
-	/* Initialize libbson */
-	bson_mem_set_vtable(&MONGODB_G(bsonMemVTable));
 	/* Initialize libmongoc */
 	mongoc_init();
+	/* Initialize libbson */
+	bson_mem_set_vtable(&MONGODB_G(bsonMemVTable));
 	mongoc_log_set_handler(php_phongo_log, ctx);
 
 	/* Prep default object handlers to be used when we register the classes */
@@ -1765,6 +1765,7 @@ PHP_MSHUTDOWN_FUNCTION(mongodb)
 {
 	(void)type; /* We don't care if we are loaded via dl() or extension= */
 
+	bson_mem_restore_vtable();
 	/* Cleanup after libmongoc */
 	mongoc_cleanup();