fix "exit" in global constructor causes the program to hang

commit 188759bb documented the intent
to allow recursive dlopen based on tracking ctor_visitor, but used a
kernel tid rather than the pthread_t to identify the caller. as a
result, it would not behave as intended under fork by a ctor, where
the child tid would not match.

Test:libc-test/src/function/exit.c
Issue:I7F2LR
Signed-off-by: Nfangting <fangting12@huawei.com>

libc-test/src/functional/exit_constructor.c

+#include <stdlib.h>
+#include "test.h"
+
+__attribute__((constructor)) 
+void B_ctor() {
+	exit(t_status); 
+}
+
+int main() {
+	return t_status;  
+}
\ No newline at end of file

libc-test/src/functional/test_src_functional.gni

@@ -80,6 +80,7 @@ functional_list = [
   "wcstol",
   "dlclose_reset",
   "atexit_dlclose",
+  "exit_constructor",
 ]
 
 if (use_pthread_cancel) {

porting/linux/user/ldso/dynlink.c

@@ -2508,7 +2508,7 @@ static void do_init_fini(struct dso **queue)
 {
 	struct dso *p;
 	size_t dyn[DYN_CNT], i;
-	int self = __pthread_self()->tid;
+	pthread_t self = __pthread_self();
 
 	pthread_mutex_lock(&init_fini_lock);
 	for (i=0; (p=queue[i]); i++) {

porting/linux/user/src/internal/dynlink.h

@@ -106,7 +106,7 @@ struct dso {
 	dev_t dev;
 	ino_t ino;
 	uint64_t file_offset;
-	int ctor_visitor;
+	pthread_t ctor_visitor;
 	char *rpath_orig, *rpath;
 	struct tls_module tls;
 	size_t tls_id;