(partially) Fix Bug#55227 Fix compiler warnings in innodb with gcc 4.6

Fix compiler warning:
btr/btr0cur.c: In function 'btr_cur_optimistic_update':
btr/btr0cur.c:1839:10: error: variable 'orig_rec' set but not used [-Werror=unused-but-set-variable]

storage/innodb_plugin/btr/btr0cur.c

@@ -1836,7 +1836,6 @@ btr_cur_optimistic_update(
 	page_t*		page;
 	page_zip_des_t*	page_zip;
 	rec_t*		rec;
-	rec_t*		orig_rec;
 	ulint		max_size;
 	ulint		new_rec_size;
 	ulint		old_rec_size;
@@ -1850,7 +1849,7 @@ btr_cur_optimistic_update(
 
 	block = btr_cur_get_block(cursor);
 	page = buf_block_get_frame(block);
-	orig_rec = rec = btr_cur_get_rec(cursor);
+	rec = btr_cur_get_rec(cursor);
 	index = cursor->index;
 	ut_ad(!!page_rec_is_comp(rec) == dict_table_is_comp(index->table));
 	ut_ad(mtr_memo_contains(mtr, block, MTR_MEMO_PAGE_X_FIX));