[gthumb] Fixed 'variabile might be clobbered' warnings

[Paolo Bacchilega <paobac src gnome org>]

commit 95ec25445fb7ac827792dac2d3f7c61b1f958702
Author: Paolo Bacchilega <paobac src gnome org>
Date:   Sun Nov 29 09:55:42 2020 +0100

    Fixed 'variabile might be clobbered' warnings

 extensions/cairo_io/cairo-image-surface-jpeg.c | 2 +-
 extensions/cairo_io/gth-image-saver-jpeg.c     | 2 +-
 extensions/cairo_io/gth-image-saver-png.c      | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/extensions/cairo_io/cairo-image-surface-jpeg.c b/extensions/cairo_io/cairo-image-surface-jpeg.c
index cc021614..b8777982 100644
--- a/extensions/cairo_io/cairo-image-surface-jpeg.c
+++ b/extensions/cairo_io/cairo-image-surface-jpeg.c
@@ -182,7 +182,7 @@ _cairo_image_surface_create_from_jpeg (GInputStream  *istream,
        guint32                        pixel;
        unsigned char                 *p_buffer;
        int                            x;
-       gboolean                       read_all_scanlines = FALSE;
+       volatile gboolean              read_all_scanlines = FALSE;
        volatile gboolean              finished = FALSE;
 
        image = gth_image_new ();
diff --git a/extensions/cairo_io/gth-image-saver-jpeg.c b/extensions/cairo_io/gth-image-saver-jpeg.c
index b59796c1..c6df5fc6 100644
--- a/extensions/cairo_io/gth-image-saver-jpeg.c
+++ b/extensions/cairo_io/gth-image-saver-jpeg.c
@@ -237,7 +237,7 @@ _cairo_surface_write_as_jpeg (cairo_surface_t  *image,
        struct jpeg_compress_struct cinfo;
        struct error_handler_data jerr;
        guchar            *buf = NULL;
-       guchar            *pixels = NULL;
+       guchar            *pixels;
        volatile int       quality = 85; /* default; must be between 0 and 100 */
        volatile int       smoothing = 0;
        volatile gboolean  optimize = FALSE;
diff --git a/extensions/cairo_io/gth-image-saver-png.c b/extensions/cairo_io/gth-image-saver-png.c
index df3292b5..050eb212 100644
--- a/extensions/cairo_io/gth-image-saver-png.c
+++ b/extensions/cairo_io/gth-image-saver-png.c
@@ -165,7 +165,7 @@ _cairo_surface_write_as_png (cairo_surface_t  *image,
                             char            **values,
                             GError          **error)
 {
-       int            compression_level;
+       volatile int   compression_level;
        int            width, height;
        gboolean       alpha;
        guchar        *pixels, *ptr, *buf;