t_signal_and_sp: Test makecontext and pthread_create stack alignment.

PR kern/59327: user stack pointer is not aligned properly

t_signal_and_sp: Fix main function on alpha so it returns zero.

PR kern/59327: user stack pointer is not aligned properly

t_signal_and_sp: Add alpha support.

Turns out alpha too gets confused by by misaligned sigaltstack, and
by misaligned sp in the interrupted code, when a signal is delivered.

PR kern/59327: user stack pointer is not aligned properly

PR kern/58149: Cannot return from a signal handler if SP was
misaligned when the signal arrived

t_signal_and_sp: Add alpha support.

Turns out alpha too gets confused by by misaligned sigaltstack, and
by misaligned sp in the interrupted code, when a signal is delivered.

PR kern/59327: user stack pointer is not aligned properly

PR kern/58149: Cannot return from a signal handler if SP was
misaligned when the signal arrived

t_signal_and_sp: Add alpha support.

Turns out alpha too gets confused by by misaligned sigaltstack, and
by misaligned sp in the interrupted code, when a signal is delivered.

PR kern/59327: user stack pointer is not aligned properly

PR kern/58149: Cannot return from a signal handler if SP was
misaligned when the signal arrived

t_signal_and_sp: Test makecontext and pthread_create stack alignment.

PR kern/59327: user stack pointer is not aligned properly