Modernize Lua library/module initialization, drop support for Lua < 5.2

Replace long since deprecated luaL_openlib() with modern counterparts
luaL_newlib() and luaL_setfuncs() and use luaL_requiref() for
loading our modules (these changes needed to go hand in hand, otherwise
it blows up every which way). Because these functions are only available
in Lua >= 5.2, this means we can drop the other compat checks as well,
just update the documenation for the new version requirement.

This also means that rpm now works on a modern Lua (tested with 5.3.5)
without requiring any compat modules and defines to be present in Lua. Whee!

Patch based on work done by @daurnimator in PR #169.

Resolves: #166

INSTALL

@@ -81,7 +81,7 @@ Minimal instructions for building BDB are
     make install
 
 For embedded Lua scripting support (recommended and enabled by default),
-you'll need Lua >= 5.1 library + development environment installed.
+you'll need Lua >= 5.2 library + development environment installed.
 Note that only the library is needed at runtime, RPM never calls external
 Lua interpreter for anything. Lua is available from 
     http://www.lua.org

luaext/lposix.c

@@ -890,7 +890,7 @@ static const luaL_Reg R[] =
 
 LUALIB_API int luaopen_posix (lua_State *L)
 {
-	luaL_openlib(L, MYNAME, R, 0);
+	luaL_newlib(L, R);
 	lua_pushliteral(L,"version");		/** version */
 	lua_pushliteral(L,MYVERSION);
 	lua_settable(L,-3);

luaext/lrexlib.c

@@ -327,14 +327,14 @@ LUALIB_API int luaopen_rex(lua_State *L)
 {
 #ifdef WITH_POSIX
   createmeta(L, "regex_t");
-  luaL_openlib(L, NULL, rexmeta, 0);
+  luaL_setfuncs(L, rexmeta, 0);
   lua_pop(L, 1);
 #endif
 #ifdef WITH_PCRE
   createmeta(L, "pcre");
-  luaL_openlib(L, NULL, pcremeta, 0);
+  luaL_setfuncs(L, pcremeta, 0);
   lua_pop(L, 1);
 #endif
-  luaL_openlib(L, "rex", rexlib, 0);
+  luaL_newlib(L, rexlib);
   return 1;
 }

rpmio/rpmlua.c

@@ -6,20 +6,11 @@
 #include <lposix.h>
 #include <lrexlib.h>
 
-#if (LUA_VERSION_NUM < 502)
-#define lua_rawlen(L, i) (lua_objlen(L, i))
-#endif
-
 #ifndef LUA_LOADED_TABLE
 /* feature introduced in Lua 5.3.4 */
 #define LUA_LOADED_TABLE "_LOADED"
 #endif
 
-/* define added in 5.2 */
-#ifndef lua_pushglobaltable
-#define lua_pushglobaltable(L)	lua_pushvalue(L, LUA_GLOBALSINDEX)
-#endif
-
 #include <unistd.h>
 #include <assert.h>
 #include <spawn.h>
@@ -145,16 +136,13 @@ rpmlua rpmluaNew()
     lua->L = L;
 
     for (lib = extlibs; lib->name; lib++) {
-	lua_pushcfunction(L, lib->func);
-	lua_pushstring(L, lib->name);
-	lua_call(L, 1, 0);
-	lua_settop(L, 0);
+	luaL_requiref(L, lib->name, lib->func, 1);
     }
     lua_pushcfunction(L, rpm_print);
     lua_setglobal(L, "print");
 
-    lua_pushglobaltable(L);
-    luaL_openlib(L, "os", os_overrides, 0);
+    lua_getglobal(L, "os");
+    luaL_setfuncs(L, os_overrides, 0);
 
     lua_getglobal(L, "package");
     lua_pushfstring(L, "%s/%s", rpmConfigDir(), "/lua/?.lua");
@@ -185,11 +173,7 @@ void rpmluaRegister(rpmlua lua, const luaL_Reg *funcs, const char *lib)
 {
     lua_getfield(lua->L, LUA_REGISTRYINDEX, LUA_LOADED_TABLE);
     lua_getfield(lua->L, -1, lib);
-#if (LUA_VERSION_NUM < 502) || defined(LUA_COMPAT_MODULE)
-    luaL_register(lua->L, 0, funcs);
-#else
     luaL_setfuncs(lua->L, funcs, 0);
-#endif
     lua_pop(lua->L, 2);
 }
 
@@ -1005,7 +989,6 @@ static const luaL_Reg rpmlib[] = {
 
 static int luaopen_rpm(lua_State *L)
 {
-    lua_pushglobaltable(L);
-    luaL_openlib(L, "rpm", rpmlib, 0);
-    return 0;
+    luaL_newlib(L, rpmlib);
+    return 1;
 }