comments re. initctl proto
move NOCALL to test.c
comments
telinit ? command formatting cleanup
test joincmd
add __WORDSIZE to limits.h

A single test, x_printf, needs it.
cast small ptrdiff to int to avoid 32/64 bit size mismatches
getdents is #219 after all
test printf use proper values for 32/64 arches
mips syscall()
mips calling convention
mips does not tolerate signed-negative address offset (?)
qemu to run tests for non-native builds