maint: pacify GCC 6 with -Wnull-dereference

src/id.c:249:29: error: potential null pointer dereference \
[-Werror=null-dereference]
       pw_name = xstrdup (pwd->pw_name);
                          ~~~^~~~~~~~~
src/whoami.c:89:11: error: potential null pointer dereference \
[-Werror=null-dereference]
   puts (pw->pw_name);
         ~~^~~~~~~~~

* src/id.c (main): Explicitly exit with EXIT_FAILURE after an eror to
help gcc-6 to detect that the dereferenced pointer is valid.
* src/whoami.c (main): Likewise.

1 files changed, 4 insertions, 1 deletions

diff --git a/src/id.c b/src/id.c
index 218ee5a31..35cbeb564 100644
--- a/src/id.c
+++ b/src/id.c
@@ -245,7 +245,10 @@ main (int argc, char **argv)
             }
         }
       if (pwd == NULL)
-        error (EXIT_FAILURE, 0, _("%s: no such user"), quote (spec));
+        {
+          error (0, 0, _("%s: no such user"), quote (spec));
+          exit (EXIT_FAILURE);
+        }
       pw_name = xstrdup (pwd->pw_name);
       ruid = euid = pwd->pw_uid;
       rgid = egid = pwd->pw_gid;