/usr/tests/lib/libc/sys/t_getcontext
/usr/tests/lib/libc/sys/t_swapcontext
/usr/tests/lib/libc/sys/t_ucontext
/usr/tests/lib/libpthread/t_swapcontext
All pass now.
Changes amount to
- saving GP from caller in context for n{32,64}
- performing (the equivalient of) PIC_PROLOGUE for swapcontext and
__resumecontext
- Call setcontext via the PLT in __resumecontext