Remove nowhere referenced file. (egrep "filename\." didn't find anything)

Signed-off-by: Domen Puncer <domen@coderock.org>

--- c/arch/alpha/lib/dbg_stackcheck.S	2004-02-04 04:45:04.000000000 +0100
+++ a/arch/alpha/lib/dbg_stackcheck.S	1970-01-01 01:00:00.000000000 +0100
@@ -1,27 +0,0 @@
-/*
- * arch/alpha/lib/stackcheck.S
- * Contributed by Richard Henderson (rth@tamu.edu)
- *
- * Verify that we have not overflowed the stack.  Oops if we have.
- */
-
-#include <asm/asm_offsets.h>
-
-	.text
-	.set noat
-
-	.align 3
-	.globl _mcount
-	.ent _mcount
-_mcount:
-	.frame $30, 0, $28, 0
-	.prologue 0
-
-	lda	$0, TASK_SIZE($8)
-	cmpult	$30, $0, $0
-	bne	$0, 1f
-	ret	($28)
-1:	stq	$31, -8($31)	# oops me, damn it.
-	br	1b
-
-	.end _mcount
