Fix opendir problem when statically linked due to a missing

initialization of the mutex field within DIR struct.
When linked dynamically instead, __pthread_mutex_init will
initialize the mutex itself. Without this fix, any call to
readdir will stuck forever trying to acquire the mutex.

Signed-off-by: Carmelo Amoroso <carmelo.amoroso@st.com>

libc/misc/dirent/opendir.c

@@ -64,6 +64,7 @@ close_and_ret:
 	if (!(ptr = malloc(sizeof(*ptr))))
 		goto nomem_close_and_ret;
 
+	memset(ptr, '\0', sizeof(DIR));
 	ptr->dd_fd = fd;
 	ptr->dd_nextloc = ptr->dd_size = ptr->dd_nextoff = 0;