ITS#8117 better fix

Don't change mc_dbx because we would need to undo the change if
the txn aborts. Make the fix (for get) match existing code for put.

libraries/liblmdb/mdb.c

@@ -5871,15 +5871,21 @@ set1:
 					return rc;
 			}
 		} else if (op == MDB_GET_BOTH || op == MDB_GET_BOTH_RANGE) {
-			MDB_val d2;
-			if ((rc = mdb_node_read(mc->mc_txn, leaf, &d2)) != MDB_SUCCESS)
+			MDB_val olddata;
+			MDB_cmp_func *dcmp;
+			if ((rc = mdb_node_read(mc->mc_txn, leaf, &olddata)) != MDB_SUCCESS)
 				return rc;
-			rc = mc->mc_dbx->md_dcmp(data, &d2);
+			dcmp = mc->mc_dbx->md_dcmp;
+#if UINT_MAX < SIZE_MAX
+			if (dcmp == mdb_cmp_int && olddata.mv_size == sizeof(size_t))
+				dcmp = mdb_cmp_clong;
+#endif
+			rc = dcmp(data, &olddata);
 			if (rc) {
 				if (op == MDB_GET_BOTH || rc > 0)
 					return MDB_NOTFOUND;
 				rc = 0;
-				*data = d2;
+				*data = olddata;
 			}
 
 		} else {
@@ -6388,16 +6394,17 @@ more:
 
 			/* Was a single item before, must convert now */
 			if (!F_ISSET(leaf->mn_flags, F_DUPDATA)) {
+				MDB_cmp_func *dcmp;
 				/* Just overwrite the current item */
 				if (flags == MDB_CURRENT)
 					goto current;
-
+				dcmp = mc->mc_dbx->md_dcmp;
 #if UINT_MAX < SIZE_MAX
-				if (mc->mc_dbx->md_dcmp == mdb_cmp_int && olddata.mv_size == sizeof(size_t))
-					mc->mc_dbx->md_dcmp = mdb_cmp_clong;
+				if (dcmp == mdb_cmp_int && olddata.mv_size == sizeof(size_t))
+					dcmp = mdb_cmp_clong;
 #endif
 				/* does data match? */
-				if (!mc->mc_dbx->md_dcmp(data, &olddata)) {
+				if (!dcmp(data, &olddata)) {
 					if (flags & MDB_NODUPDATA)
 						return MDB_KEYEXIST;
 					/* overwrite it */