add compiled features into --version output (#462)

a lot of application which allow selecting features at build time seem
to output the build config with `--version` or similar (e.g ffmpeg).

aside from giving the user information about the feature set the binary
was compiled with (in case the user didn't compile it themselves, e.g on
a binary distro) it can also (possibly) help when submitting bug
reports.

Reviewed-on: https://codeberg.org/nsxiv/nsxiv/pulls/462
Reviewed-by: explosion-mental <explosion-mental@noreply.codeberg.org>

image.c

@@ -33,15 +33,6 @@
 #include <libexif/exif-data.h>
 #endif
 
-#ifdef IMLIB2_VERSION
-	#if IMLIB2_VERSION >= IMLIB2_VERSION_(1, 8, 0)
-		#define HAVE_IMLIB2_MULTI_FRAME 1
-	#endif
-#endif
-#ifndef HAVE_IMLIB2_MULTI_FRAME
-	#define HAVE_IMLIB2_MULTI_FRAME 0
-#endif
-
 #if HAVE_LIBGIF && !HAVE_IMLIB2_MULTI_FRAME
 #include <gif_lib.h>
 enum { DEF_GIF_DELAY = 75 };

nsxiv.h

@@ -159,6 +159,15 @@ typedef keymap_t button_t;
 
 /* image.c */
 
+#ifdef IMLIB2_VERSION
+	#if IMLIB2_VERSION >= IMLIB2_VERSION_(1, 8, 0)
+		#define HAVE_IMLIB2_MULTI_FRAME 1
+	#endif
+#endif
+#ifndef HAVE_IMLIB2_MULTI_FRAME
+	#define HAVE_IMLIB2_MULTI_FRAME 0
+#endif
+
 typedef struct {
 	Imlib_Image im;
 	unsigned int delay;

options.c

@@ -50,6 +50,27 @@ void print_usage(void)
 static void print_version(void)
 {
 	printf("%s %s\n", progname, VERSION);
+	fputs("features: "
+#if HAVE_INOTIFY
+		"+inotify "
+#endif
+#if HAVE_LIBFONTS
+		"+statusbar "
+#endif
+#if HAVE_LIBEXIF
+		"+exif "
+#endif
+#if HAVE_IMLIB2_MULTI_FRAME
+		"+multiframe "
+#else
+	#if HAVE_LIBGIF
+		"+giflib "
+	#endif
+	#if HAVE_LIBWEBP
+		"+libwebp "
+	#endif
+#endif
+		"\n", stdout);
 }
 
 void parse_options(int argc, char **argv)