merge-index: fix longstanding bug in merging symlinks

Ancient commit e2b6a9d0 added code to pass "file modes" from
merge-index to merge-one-file, and then later commit 54dd99a1
wanted to make sure we do not end up creating a nonsense symlink
that points at a path whose name contains conflict markers.

However, nobody noticed that the code in merge-index added by
e2b6a9d0 were stripping the S_IFMT bits and the code in 54dd99a1
was meaningless.  This fixes it.
Signed-off-by: NJunio C Hamano <junkio@cox.net>

merge-index.c

@@ -60,7 +60,7 @@ static int merge_entry(int pos, const char *path)
 			break;
 		found++;
 		strcpy(hexbuf[stage], sha1_to_hex(ce->sha1));
-		sprintf(ownbuf[stage], "%o", ntohl(ce->ce_mode) & (~S_IFMT));
+		sprintf(ownbuf[stage], "%o", ntohl(ce->ce_mode));
 		arguments[stage] = hexbuf[stage];
 		arguments[stage + 4] = ownbuf[stage];
 	} while (++pos < active_nr);