add Lua to Qt's "About nethack"

Add "Lua" and its version number of the 'About' popup.  No copyright
information is included since neither nethack's nor Qt's is shown.

Lua copyright text is included in the output of '#version'.

win/Qt/qt_main.cpp

@@ -459,7 +459,7 @@ aboutMsg()
     char *p, vbuf[BUFSZ];
     /* nethack's getversionstring() includes a final period
        but we're using it mid-sentence so strip period off */
-    if ((p = strrchr(getversionstring(vbuf), '.')) != 0 && *(p + 1) == '\0')
+    if ((p = strrchr(::getversionstring(vbuf), '.')) != 0 && *(p + 1) == '\0')
         *p = '\0';
     /* it's also long; break it into two pieces */
     (void) strsubst(vbuf, " - ", "\n- ");
@@ -471,7 +471,7 @@ aboutMsg()
 #endif
         " the Qt %d GUI toolkit.\n"                      // short Qt version
         "\n"
-        "This is %s%s.\n"       // long nethack version and full Qt version
+        "This is %s%s and Lua %s.\n" // long nethack version, Qt & Lua versions
         "\n"
         "NetHack's Qt interface originally developed by Warwick Allison.\n"
         "\n"
@@ -486,6 +486,7 @@ aboutMsg()
 #else
         "Qt:\n     http://www.troll.no/\n"      // obsolete
 #endif
+        "Lua:\n     https://lua.org/\n"
         "NetHack:\n     %s\n", // DEVTEAM_URL
         // arguments
 #ifdef QT_VERSION_MAJOR
@@ -499,6 +500,7 @@ aboutMsg()
 #else
         "",
 #endif
+        ::get_lua_version(),
         DEVTEAM_URL);
     return msg;
 }