aout32 coredump compat fix

dump_seek() does SEEK_CUR, not SEEK_SET; native binfmt_aout
handles it correctly (seeks by PAGE_SIZE - sizeof(struct user),
getting the current position to PAGE_SIZE), compat one seeks
by PAGE_SIZE and ends up at PAGE_SIZE + already written...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/x86/ia32/ia32_aout.c

@@ -192,7 +192,7 @@ static int aout_core_dump(long signr, struct pt_regs *regs, struct file *file,
 	/* struct user */
 	DUMP_WRITE(&dump, sizeof(dump));
 	/* Now dump all of the user data.  Include malloced stuff as well */
-	DUMP_SEEK(PAGE_SIZE);
+	DUMP_SEEK(PAGE_SIZE - sizeof(dump));
 	/* now we start writing out the user space info */
 	set_fs(USER_DS);
 	/* Dump the data area */