lua: Migrate to gentargets and improve it

Closes #803

Based on initial patch by rvpaasen@t3i.nl

[Peter: lua/luac needs liblua.so.* on target]
Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/lua/lua-debug_getfenv.patch

@@ -0,0 +1,10 @@
+--- lua-5.1.4.orig/src/ldblib.c	2007/12/28 15:32:23	2.63.1.3
++++ lua-5.1.4/src/ldblib.c	2010/02/23 12:36:59
+@@ -45,6 +45,7 @@
+ 
+ 
+ static int db_getfenv (lua_State *L) {
++  luaL_checkany(L, 1);
+   lua_getfenv(L, 1);
+   return 1;
+ }