res_pjsip_session.c: Fix compiler warnings.

AST_VECTOR_SIZE() returns a size_t.  This is not always equivalent to an
unsigned long on all machines.

Change-Id: I0a4189a104e6e3a2e2273de06620eaef19df9338

res/res_pjsip_session.c

@@ -5583,12 +5583,14 @@ static int test_is_media_state_equal(struct ast_sip_session_media_state *left, s
 	}
 	if (AST_VECTOR_SIZE(&left->sessions) != AST_VECTOR_SIZE(&right->sessions)) {
 		ast_assert(!assert_on_failure);
-		SCOPE_EXIT_RTN_VALUE(0, "session vector sizes different: left %lu != right %lu\n", AST_VECTOR_SIZE(&left->sessions),
+		SCOPE_EXIT_RTN_VALUE(0, "session vector sizes different: left %zu != right %zu\n",
+			AST_VECTOR_SIZE(&left->sessions),
 			AST_VECTOR_SIZE(&right->sessions));
 	}
 	if (AST_VECTOR_SIZE(&left->read_callbacks) != AST_VECTOR_SIZE(&right->read_callbacks)) {
 		ast_assert(!assert_on_failure);
-		SCOPE_EXIT_RTN_VALUE(0, "read_callback vector sizes different: left %lu != right %lu\n", AST_VECTOR_SIZE(&left->read_callbacks),
+		SCOPE_EXIT_RTN_VALUE(0, "read_callback vector sizes different: left %zu != right %zu\n",
+			AST_VECTOR_SIZE(&left->read_callbacks),
 			AST_VECTOR_SIZE(&right->read_callbacks));
 	}