Add write error checks

wtfstopw.asm

 	mov rsi, cr
 	mov rdx, 1
 	syscall ; \r on stderr
+	test rax, rax
+	js fault
 
 	mov rax, 1
 	mov rdi, 1
 	mov rsi, lapsmsg
 	mov rdx, 4 ; "Lap "
 	syscall
+	test rax, rax
+	js fault
 
 	; increment the lapcount str directly
 	mov rcx, lapcountlen - 1; digit counter starting by the right most
 	mov rax, 1
 	mov rdi, 1 ; stdout
 	syscall
+	test rax, rax
+	js fault
 
 	mov rax, 1 ; write
 	mov rsi, lapsmsg + 3
 	mov rdx, 3 ; " : "
 	syscall
+	test rax, rax
+	js fault
 
 	std ; set DF for string operations
 	push 1 ; stdout