Added getpid system call

src/drivers/nulldrv/main.s

@@ -1,11 +1,19 @@
 global _start
 _start:
 	xor rbp, rbp	; Sentinel rbp
+
+	mov rax, 5		; GETPID syscall
+	int 0xee
+	mov r12, rax	; save pid to r12
+
+	mov rax, 1		; DEBUG syscall
+	int 0xee
+
 	mov r11, 0		; counter
 	mov rbx, 20		; sleep timeout
 
 .loop:
-	mov rax, 1		; DEBUG syscall
+	mov rax, 2		; MESSAGE syscall
 	;mov rax, 0		; NOOP syscall
 	;syscall
 	int 0xee