Fix session changeset procesing (reverting some of 0d748ad changes)

This removes strdup from Lua SQLite wrapper, as it's applied to binary changeset
strings, thus cutting them short (because of strlen).

tool/net/lsqlite3.c

@@ -2312,7 +2312,7 @@ static int db_concat_changeset(lua_State *L) {
     int rc = sqlite3changegroup_new(&pGrp);
     for (int i = 1; rc == SQLITE_OK && i <= n; i++) {
         lua_rawgeti(L, 2, i);
-        cset = gc(strdup(lua_tostring(L, -1)));
+        cset = (void *)lua_tostring(L, -1);
         nset = lua_rawlen(L, -1);
         rc = sqlite3changegroup_add(pGrp, nset, cset);
         lua_pop(L, 1);  // pop the string
@@ -2328,7 +2328,7 @@ static int db_concat_changeset(lua_State *L) {
 
 static int db_apply_changeset(lua_State *L) {
     sdb *db = lsqlite_checkdb(L, 1);
-    char *cset = gc(strdup(luaL_checkstring(L, 2)));
+    void *cset = (void *)luaL_checkstring(L, 2);
     int nset = lua_rawlen(L, 2);
     int top = lua_gettop(L);
     int rc;