move initialization of error_backtrace to handle NTS

Co-authored-by: Niels Dossche <7771979+nielsdos@users.noreply.github.com>

Author: ericnorris

Zend/zend.c

@@ -812,7 +812,6 @@ static void executor_globals_ctor(zend_executor_globals *executor_globals) /* {{
 	executor_globals->in_autoload = NULL;
 	executor_globals->current_execute_data = NULL;
 	executor_globals->current_module = NULL;
-	ZVAL_UNDEF(&executor_globals->error_backtrace);
 	executor_globals->exit_status = 0;
 #if XPFPA_HAVE_CW
 	executor_globals->saved_fpu_cw = 0;

Zend/zend_execute_API.c

@@ -140,6 +140,8 @@ void init_executor(void) /* {{{ */
 	original_sigsegv_handler = signal(SIGSEGV, zend_handle_sigsegv);
 #endif
 
+	ZVAL_UNDEF(&EG(error_backtrace));
+
 	EG(symtable_cache_ptr) = EG(symtable_cache);
 	EG(symtable_cache_limit) = EG(symtable_cache) + SYMTABLE_CACHE_SIZE;
 	EG(no_extensions) = 0;