[ghex] Fix further format string warnings

[Logan Rathbone <larathbone src gnome org>]

commit eb1900a579d6336e77942ae3d1b5804aceaf17ac
Author: Logan Rathbone <poprocks gmail com>
Date:   Mon Jan 10 17:18:19 2022 -0500

    Fix further format string warnings
    
    See !24

 src/gtkhex.c          |  6 +++++-
 src/hex-buffer-mmap.c | 10 +++++++---
 2 files changed, 12 insertions(+), 4 deletions(-)
---
diff --git a/src/gtkhex.c b/src/gtkhex.c
index 48a0e39..c34b57f 100644
--- a/src/gtkhex.c
+++ b/src/gtkhex.c
@@ -1132,10 +1132,14 @@ render_offsets (HexWidget *self,
        snprintf (fmt, BUFLEN-1, "%%0%dlX", off_cpl); 
        hex_widget_layout_set_offset_cpl (HEX_WIDGET_LAYOUT(self->layout_manager), off_cpl);
 
-       for (int i = min_lines; i <= max_lines; i++) {
+       for (int i = min_lines; i <= max_lines; i++)
+       {
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wformat-nonliteral"
                /* generate offset string and place in temporary buffer */
                sprintf(off_str, fmt,
                                (self->top_line + i) * self->cpl + STARTING_OFFSET);
+#pragma GCC diagnostic pop
 
                /* build pango layout for offset line; draw line with gtk. */
                pango_layout_set_text (self->olayout, off_str, off_cpl);
diff --git a/src/hex-buffer-mmap.c b/src/hex-buffer-mmap.c
index bb49d5d..5bd07f5 100644
--- a/src/hex-buffer-mmap.c
+++ b/src/hex-buffer-mmap.c
@@ -171,14 +171,18 @@ set_error (HexBufferMmap *self, const char *blurb)
         * (eg, 'No such file or directory').
         */
                message = g_strdup_printf (_("%s: %s"), blurb, g_strerror (errno));
-               g_debug ("%s: %s", __func__, message);
        }
+       else
+       {
+               message = g_strdup (blurb);
+       }
+       g_debug ("%s: %s", __func__, message);
 
        g_set_error (&self->error,
                        HEX_BUFFER_MMAP_ERROR,
                        errno,
-                       message ? message : blurb,
-                       g_strerror (errno));
+                       "%s",
+                       message);
 
        if (errno)
                self->last_errno = errno;