add a new System call in minix3

you can refer to the PDF

note that in the table.c , it's do_printmessage
instead of do_printmessage()

the image is 3.1.2ar1_20080321

running Minix3 on Qemu 0.8.2

if you try to run minix3 on qemu
you only can use qemu0.8.2

if you try to download latest qemu from its official website
(in my example , 0.9.1) it will hang after launching minix

i do as the webpage
WIKI page on MINIX3
says

and i found that you need to download the bzip2 ISO from MINIX3 website
At first i use zip format ISO , in the end i found i can not use 'packman' to install packages

there's also another nice webpage to illustrate install minix3 on qemu
algo2c's blog



thank God!