Drop cgetclose() from getdiskbyname().

This was a local addition to the original change from NetBSD.
Being this libc there is some chance for it to interfere with
user's cget*() functions usage. The memory leak was finely
plugged by r278300.

Pointed out by:	ache

lib/libc/gen/disklabel.c

@@ -162,6 +162,5 @@ getdiskbyname(const char *name)
 	dp->d_magic = DISKMAGIC;
 	dp->d_magic2 = DISKMAGIC;
 	free(buf);
-	(void)cgetclose();
 	return (dp);
 }