Remove broken open_url() hack.

The embedded fltk version works fine.

FL/About_Dialog.fl

@@ -13,15 +13,7 @@ decl {\#include <FL/filename.H>} {private local
 
 Function {open_url( const char *url )} {open return_type void
 } {
-  code {\#if ! ( FL_MAJOR_VERSION >= 1 && FL_MINOR_VERSION >= 1 && FL_PATCH_VERSION >= 8 )
-
-	// FIXME: got a better idea?
-	char cmd[256];
-	snprintf( cmd, sizeof( cmd ), "x-www-browser '%s' &", url );
-	system( cmd );
-\#else
-	fl_open_uri( url );
-\#endif} {}
+  code {fl_open_uri( url );} {}
 } 
 
 class About_Dialog {open