Only look for one single version of Lua: the one pointed to by the
pkgconfig package 'lua'. The wrapper set up by lua eclasses will take care
of the rest.

--- a/configure.ac	2021-06-11 12:20:01.222417096 +0200
+++ b/configure.ac	2021-06-11 12:21:00.257419197 +0200
@@ -1907,44 +1907,10 @@
     [disable LUA scripting support (default enabled)]))
 if test "${enable_lua}" != "no"
 then
-  PKG_CHECK_MODULES(LUA, lua5.2, [ have_lua=yes ], [:])
-
-  AS_IF([test "${have_lua}" != "yes"], [
-    AC_MSG_WARN([${LUA_PKG_ERRORS}, trying lua 5.1 instead])
-    PKG_CHECK_MODULES(LUA, lua5.1, [ have_lua=yes ], [:]) ])
-
-  AS_IF([test "${have_lua}" != "yes"], [
-    AC_MSG_WARN([${LUA_PKG_ERRORS}, trying lua >= 5.1 instead])
-    PKG_CHECK_MODULES(LUA, lua >= 5.1, [ have_lua=yes ], [:]) ])
-
-  AS_IF([test "${have_lua}" != "yes"], [
-     AC_MSG_WARN([${LUA_PKG_ERRORS}, trying manual detection instead])
-     have_lua_lib=no
-     AC_CHECK_LIB( lua5.2 , luaL_newstate, [
-       LUA_LIBS="-llua5.2"
-       have_lua_lib=yes], [])
-
-     AS_IF([test "${have_lua_lib}" != "yes"], [
-       AC_CHECK_LIB( lua5.1 , luaL_newstate, [
-         LUA_LIBS="-llua5.1"
-         have_lua_lib=yes], [] ) ])
-
-     AS_IF([test "${have_lua_lib}" != "yes"], [
-       AC_CHECK_LIB( lua51 , luaL_newstate, [
-         LUA_LIBS="-llua51"
-         have_lua_lib=yes], [] ) ])
-
-     AS_IF([test "${have_lua_lib}" != "yes"], [
-       AC_CHECK_LIB( lua , luaL_newstate,
-         [LUA_LIBS="-llua"
-          have_lua_lib=yes],
-         [ have_lua=no ], [-lm] ) ])
-
-     dnl If we found any lib, check that we have the headers too
-     AS_IF([test "${have_lua_lib}" = "yes"], [
-       AC_CHECK_HEADERS([lua.h lauxlib.h lualib.h], [ have_lua=yes ], []) ])
-  ])
-
+  PKG_CHECK_MODULES(LUA, lua,
+    [ have_lua=yes ],
+    [ have_lua=no ]
+    )
   if test "x${have_lua}" != "xyes" ;  then
       AC_MSG_ERROR([Could not find lua. Lua is needed for some interfaces (rc, telnet, http) as well as many other custom scripts. Use --disable-lua to ignore this error.])
   fi