xv6: comment out thread_test in Makefile
xv6: comment out thread_test in Makefile

You should uncomment this if you intend to do the kernel threads section.

Signed-off-by: William Katsak <9f8ee2428c051c2cbc1aeace8b3c786049771b49@cs.rutgers.edu>

MrHohn/CS-OperatingSystem-hw2,MrHohn/CS-OperatingSystem-hw2,MrHohn/cs518hw2,MrHohn/CS-OperatingSystem-hw2,MrHohn/cs518hw2,MrHohn/cs518hw2,MrHohn/CS-OperatingSystem-hw2,MrHohn/cs518hw2