alpha: unbreak OSF/1 (a.out) binaries

OSF/1 brk(2) was broken by following one-liner in sys_brk()
(commit 4cc6028d):

-	if (brk < mm->end_code)
+	if (brk < mm->start_brk)
		goto out;

The problem is that osf_set_program_attributes()
does update mm->end_code, but not mm->start_brk,
which still contains inappropriate value left from
binary loader, so brk() always fails.
Signed-off-by: NIvan Kokshaysky <ink@jurassic.park.msu.ru>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

arch/alpha/kernel/osf_sys.c

@@ -75,6 +75,7 @@ osf_set_program_attributes(unsigned long text_start, unsigned long text_len,
 	lock_kernel();
 	mm = current->mm;
 	mm->end_code = bss_start + bss_len;
+	mm->start_brk = bss_start + bss_len;
 	mm->brk = bss_start + bss_len;
 #if 0
 	printk("set_program_attributes(%lx %lx %lx %lx)\n",