fix gcc warnings about uninitialized variables

like:

src/shared/install.c: In function ‘unit_file_lookup_state’:
src/shared/install.c:1861:16: warning: ‘r’ may be used uninitialized in
this function [-Wmaybe-uninitialized]
         return r < 0 ? r : state;
                ^
src/shared/install.c:1796:13: note: ‘r’ was declared here
         int r;
             ^

1 files changed, 1 insertions, 1 deletions

diff --git a/src/libsystemd/sd-login/sd-login.c b/src/libsystemd/sd-login/sd-login.c
index f71749f72d..cc0677bdf2 100644
--- a/src/libsystemd/sd-login/sd-login.c
+++ b/src/libsystemd/sd-login/sd-login.c
@@ -82,7 +82,7 @@ _public_ int sd_pid_get_owner_uid(pid_t pid, uid_t *uid) {
 }
 
 _public_ int sd_peer_get_session(int fd, char **session) {
-        struct ucred ucred;
+        struct ucred ucred = {};
         int r;
 
         assert_return(fd >= 0, -EINVAL);