coredump: factor out the setting of PF_DUMPCORE

Cleanup.  Every linux_binfmt->core_dump() sets PF_DUMPCORE, move this into
zap_threads() called by do_coredump().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Mandeep Singh Baines <msb@chromium.org>
Cc: Neil Horman <nhorman@redhat.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index e32344b..34a9771 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -2092,8 +2092,7 @@
 		goto cleanup;
 
 	has_dumped = 1;
-	current->flags |= PF_DUMPCORE;
-  
+
 	fs = get_fs();
 	set_fs(KERNEL_DS);