Fixes for GCC 15.

--- 0.999/src/xsane-gamma.c	2022-03-30 20:37:11.000000000 +0100
+++ 0.999/src/xsane-gamma.c	2025-07-07 15:46:32.321030354 +0100
@@ -553,7 +553,7 @@
 
 /* ---------------------------------------------------------------------------------------------------------------------- */
 
-static gint xsane_batch_scan_gamma_event()
+static gint xsane_batch_scan_gamma_event(gpointer data)
 {
   DBG(DBG_proc, "xsane_batch_scan_gamma_event\n");
 
@@ -567,7 +567,7 @@
 
 /* ---------------------------------------------------------------------------------------------------------------------- */
 
-static gint xsane_slider_hold_event()
+static gint xsane_slider_hold_event(gpointer data)
 {
   DBG(DBG_proc, "xsane_slider_hold_event\n");
 
--- 0.999/src/xsane-save.h	2022-03-30 20:37:11.000000000 +0100
+++ 0.999/src/xsane-save.h	2025-07-07 15:43:56.581399783 +0100
@@ -50,7 +50,7 @@
 
 
 extern int xsane_create_secure_file(const char *filename);
-extern void xsane_cancel_save();
+extern void xsane_cancel_save(int *cancel_save);
 extern void xsane_convert_text_to_filename(char **filename);
 extern int xsane_get_filesize(char *filename);
 extern void xsane_ensure_counter_in_filename(char **filename, int counter_len);