Fix libc.a undefined symbol

Add define to differentice between gn and cmake.

https://gitee.com/openharmony/third_party_musl/issues/I6WT07Signed-off-by: Nliuyaning <liuyaning7@huawei.com>

musl_template.gni

@@ -149,6 +149,7 @@ template("musl_libs") {
     cflags = cflags_all
 
     defines = [ "BROKEN_VFP_ASM" ]
+    defines += [ "FEATURE_ATEXIT_CB_PROTECT" ]
     if (is_standard_system) {
       defines += [
         "OHOS_DNS_PROXY_BY_NETSYS=1",

porting/linux/user/ldso/dynlink.c

@@ -3577,7 +3577,9 @@ static int dlclose_impl(struct dso *p)
 	}
 
 	/* after destruct, invalidate atexit funcs which belong to this dso */
+#if (defined(FEATURE_ATEXIT_CB_PROTECT))
 	invalidate_exit_funcs(p);
+#endif
 
 	/* remove dso symbols from global list */
 	if (p->syms_next) {

porting/linux/user/src/exit/atexit.c

@@ -76,6 +76,7 @@ int __cxa_atexit(void (*func)(void *), void *arg, void *dso)
 	if (!head) head = &builtin;
 
 	// if called from atexit, check callback ptr mem range.
+#if (defined(FEATURE_ATEXIT_CB_PROTECT))
 	if ((func == (void *)call) && (dso == NULL)) {
 		p = addr2dso((size_t)arg);
 		if (p == NULL) {
@@ -84,6 +85,7 @@ int __cxa_atexit(void (*func)(void *), void *arg, void *dso)
 			return -1;
 		}
 	}
+#endif
 
 	/* If the current function list is full, add a new one */
 	if (slot==COUNT) {
@@ -140,4 +142,4 @@ int invalidate_exit_funcs(struct dso *p)
 	UNLOCK(lock);
 
 	return 0;
-}
+}
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