BuildSystem: Enable Lua 5.4.

Note to maintainers: Lua 5.4, Lua 5.3, and Lua 5.2 have not been tested
at runtime with pbx_lua. Until then, use the lowest available version
of Lua, if you enabled the module pbx_lua at all.

Change-Id: Ie5270448b11fcb4e2a53d899e4fe7fea793ce7e0

configure

@@ -29630,7 +29630,7 @@ fi
-for ver in 5.3 5.2 5.1; do
+for ver in 5.4 5.3 5.2 5.1; do
 if test "x${PBX_LUA}" != "x1" -a "${USE_LUA}" != "no"; then
    pbxlibdir=""

configure.ac

@@ -2557,7 +2557,7 @@ if test -z "$__opus_include" -o x"$__opus_include" = x" " ; then
 fi
 AST_EXT_LIB_CHECK([OPUSFILE], [opusfile], [op_open_callbacks], [opus/opusfile.h], [], [$__opus_include])
 
-for ver in 5.3 5.2 5.1; do
+for ver in 5.4 5.3 5.2 5.1; do
 	AST_EXT_LIB_CHECK([LUA], lua${ver}, [luaL_newstate], lua${ver}/lua.h, [-lm])
 	if test "x${PBX_LUA}" = "x1" ; then
 		if test x"${LUA_DIR}" = x; then