Add new tests signal[23] in t_ptrace_wait{,3,4,6,id,pid}

signal2:
    Verify that masking SIGTRAP in tracee stops tracer from
    catching this raised signal

signal3:
    Verify that masking SIGTRAP in tracee does not stop tracer from
    catching software breakpoints

signal3 is marked as failing and refrenced with PR kern/51918
Currently signal3 requires code for other architectures than x86_64

Sponsored by <The NetBSD Foundation>

(kamil)