src: Quiet a few gcc -Wmaybe-uninitialized warnings

GCC (at least 5.2.1) isn't smart enough to figure out these are always
initialized.

src/app/main.c

@@ -234,7 +234,7 @@ main (int    argc,
   if (!command->fn)
     {
       GOptionContext *context;
-      gs_free char *help;
+      gs_free char *help = NULL;
 
       context = option_context_new_with_commands ();
 

src/app/rpmostree-builtin-compose.c

@@ -106,7 +106,7 @@ rpmostree_builtin_compose (int argc, char **argv, GCancellable *cancellable, GEr
   if (!subcommand->name)
     {
       GOptionContext *context;
-      gs_free char *help;
+      gs_free char *help = NULL;
 
       context = compose_option_context_new_with_commands ();
 

src/app/rpmostree-builtin-db.c

@@ -167,7 +167,7 @@ rpmostree_builtin_db (int argc, char **argv, GCancellable *cancellable, GError *
   if (!subcommand->name)
     {
       GOptionContext *context;
-      gs_free char *help;
+      gs_free char *help = NULL;
 
       context = rpm_option_context_new_with_commands ();
 

src/daemon/rpmostreed-transaction.c

@@ -190,7 +190,7 @@ transaction_progress_changed_cb (OstreeAsyncProgress *progress,
   GVariant *arg_content;
   GVariant *arg_transfer;
 
-  g_autofree gchar *status;
+  g_autofree gchar *status = NULL;
 
   /* If there is a status that is all we output */
   status = ostree_async_progress_get_status (progress);

src/libpriv/rpmostree-rpm-util.c

@@ -920,7 +920,7 @@ void
 rpmostree_print_transaction (HifContext   *hifctx)
 {
   guint i;
-  g_autoptr(GPtrArray) install;
+  g_autoptr(GPtrArray) install = NULL;
 
   install = hif_goal_get_packages (hif_context_get_goal (hifctx),
                                    HIF_PACKAGE_INFO_INSTALL,