feat: CLI-only version (without GTK)

Modify the build system and the source
files to support building a CLI-only
version with only glib2 as a dependency.
Use CLI_ONLY=1 ./configure, then make clean all.

rs01-includes.h

@@ -23,6 +23,7 @@
 #ifndef RS01INCLUDES_H
 #define RS01INCLUDES_H
 
+#ifndef CLI
 /* Data structs from rs01-window.c */
 
 typedef struct
@@ -96,6 +97,7 @@ typedef struct
    int    dataBytes;
    int    percent, lastPercent;
 } RS01Widgets;
+#endif
 
 /*
  * local working closure for internal checksums
@@ -105,6 +107,7 @@ typedef struct
 {  struct MD5Context md5ctxt;   /* Complete image checksum */
 } RS01CksumClosure;
 
+#ifndef CLI
 /* 
  * These are exported via the Method struct 
  */
@@ -120,6 +123,7 @@ void RS01ShowCurveButton(Method*);
 
 void ResetRS01VerifyWindow(Method*);
 void CreateRS01VerifyWindow(Method*, GtkWidget*);
+#endif
 
 /*
  * These are exported (resp. only used) in ecc-rs01.c and rs01*.c
@@ -155,11 +159,13 @@ void RS01Create(void);
 
 void RS01Fix(Image*);
 
+#ifndef CLI
 /* rs01-window.c */
 
 void RS01AddFixValues(RS01Widgets*, int, int);
 void RS01SetFixMaxValues(RS01Widgets*, int, int, gint64);
 void RS01UpdateFixResults(RS01Widgets*, gint64, gint64);
+#endif
 
 /* rs01-verify.c */