branches/zip: Function fseg_free() is no longer defined

in branches/zip. To port fix for bug #48469 to zip,
we can use btr_free_root() which frees the page,
and also does not require mini-transaction.

Approved by Marko.

btr/btr0btr.c

@@ -794,8 +794,7 @@ btr_create(
 				 PAGE_HEADER + PAGE_BTR_SEG_LEAF, mtr)) {
 			/* Not enough space for new segment, free root
 			segment before return. */
-			fseg_free(space, page_no,
-				    PAGE_HEADER + PAGE_BTR_SEG_TOP);
+			btr_free_root(space, zip_size, page_no, mtr);
 
 			return(FIL_NULL);
 		}