lua.m4: clean up file

- Rely on pkg-config or pkgconf instead of lua-config when querying
  lua's build config: lua-config is no longer distributed with many
  distributions.
- Bump the minimum version of lua to 5.3 (the last 5.2 release was
  in 2015).

Signed-off-by: Enji Cooper <ngie@FreeBSD.org>

m4/lua.m4

@@ -33,37 +33,30 @@ dnl Helper macro to detect Lua in a variety of systems.
 dnl
 AC_DEFUN([KYUA_LUA], [
     lua_found=no
-
-    for lua_release in ${LUA_VERSION:-5.4 5.3 5.2 5.1}; do
-        if test "${lua_found}" = no; then
+    for lua_release in ${LUA_VERSION:-5.4 5.3}; do
+        AS_IF([test "${lua_found}" = no],[
             PKG_CHECK_MODULES([LUA], [lua${lua_release} >= ${lua_release}],
-                              [lua_found=yes], [true])
-        fi
-        if test "${lua_found}" = no; then
+                              [lua_found="lua${lua_release}"; break],[])
+        ])
+        AS_IF([test "${lua_found}" = no],[
             PKG_CHECK_MODULES([LUA], [lua-${lua_release} >= ${lua_release}],
-                              [lua_found=yes], [true])
-        fi
-        if test "${lua_found}" = no; then
+                              [lua_found="lua-${lua_release}"; break],[])
+        ])
+        AS_IF([test "${lua_found}" = no],[
             PKG_CHECK_MODULES([LUA], [lua >= ${lua_release}],
-                              [lua_found=yes], [true])
-        fi
-
-        test "${lua_found}" = no || break
+                              [lua_found=lua; break],[])
+        ])
     done
 
-    if test "${lua_found}" = no; then
-        AC_PATH_PROGS([LUA_CONFIG], [lua-config], [unset])
-        if test "${LUA_CONFIG}" != unset; then
-            AC_SUBST([LUA_CFLAGS], [$(${LUA_CONFIG} --include)])
-            AC_SUBST([LUA_LIBS], [$(${LUA_CONFIG} --libs)])
-            lua_found=yes
-        fi
-    fi
+    AS_IF([test "${lua_found}" = no],[],[
+        AC_SUBST([LUA_CFLAGS], [$(${PKG_CONFIG} --cflags ${lua_found})])
+        AC_SUBST([LUA_LIBS], [$(${PKG_CONFIG} --libs ${lua_found})])
+        ])
 
-    if test "${lua_found}" = no; then
-        AC_MSG_ERROR([lua (5.1 or newer) is required])
-    else
-        AC_MSG_NOTICE([using LUA_CFLAGS = ${LUA_CFLAGS}])
-        AC_MSG_NOTICE([using LUA_LIBS = ${LUA_LIBS}])
-    fi
+    AS_IF([test "${lua_found}" = no],
+        [AC_MSG_ERROR([lua (5.3 or newer) is required])],
+        [
+AC_MSG_NOTICE([using LUA_CFLAGS = ${LUA_CFLAGS}])
+AC_MSG_NOTICE([using LUA_LIBS = ${LUA_LIBS}])
+    ])
 ])