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/test/test-pty.c b/src/test/test-pty.c
index eadecb99a0..b5f4d4f094 100644
--- a/src/test/test-pty.c
+++ b/src/test/test-pty.c
@@ -95,7 +95,7 @@ static void run_parent(Pty *pty) {
 
 static void test_pty(void) {
         pid_t pid;
-        Pty *pty;
+        Pty *pty = NULL;
 
         rcvsiz = 0;
         zero(rcvbuf);