core: define author name/email as constants

This fixes the following compiler warning:

src/core/core-args.c:180: warning: Message contains an embedded email address.  Better move it out of the translatable string, see https://www.gnu.org/software/gettext/manual/html_node/No-embedded-URLs.html

src/core/core-args.c

@@ -178,12 +178,14 @@ args_display_copyright (void)
         stdout,
         /* TRANSLATORS: "%s %s" after "compiled on" is date and time */
         _("WeeChat %s Copyright %s, compiled on %s %s\n"
-          "Developed by Sébastien Helleu <flashcode@flashtux.org> "
+          "Developed by %s <%s> "
           "- %s"),
         version_get_version_with_git (),
         WEECHAT_COPYRIGHT_DATE,
         version_get_compilation_date (),
         version_get_compilation_time (),
+        WEECHAT_AUTHOR_NAME,
+        WEECHAT_AUTHOR_EMAIL,
         WEECHAT_WEBSITE);
     string_fprintf (stdout, "\n");
 }

src/core/weechat.h

@@ -56,6 +56,8 @@
 #define WEECHAT_COPYRIGHT_DATE   "(C) 2003-2026"
 #define WEECHAT_WEBSITE          "https://weechat.org/"
 #define WEECHAT_WEBSITE_DOWNLOAD "https://weechat.org/download/"
+#define WEECHAT_AUTHOR_NAME      "Sébastien Helleu"
+#define WEECHAT_AUTHOR_EMAIL     "flashcode@flashtux.org"
 
 /* log file */
 #define WEECHAT_LOG_NAME "weechat.log"