Planned new tracers and utilities based on top of picotrace(2), dedicated for
the NetBSD kernel:

 - fakeroot
 - fakechroot
 - strace
 - xtrace (X tracing) https://github.com/deepfire/xtrace
 - ltrace https://github.com/dkogan/ltrace
 - ftrace https://github.com/sciencemanx/ftrace
 - Xstracer for a dynamic language bindings:
   - luastracer Lua bindings
   - pystracer Python bindings
   - rubystracer Ruby bindings
   - perlstracer Perl bindings
 - fdclose https://github.com/briceburg/fdclose
 - ligth gdb-server under a distinct name
 - ptrace-jail
 - ptrace-pledge

Add regression tests.

picotrace:

 * add kernel support for overwriting syscall arguments, return values,
   error value
 * no new changes planned for currently (as of NetBSD 8.99.38) supported kernel
   features

coredumper:

 * add an option to emit backtraces

truss:

 * decode the unhandled syscalls
 * refactor the code and drop hardcoded, but not previsely specified length of
   emitted report

common:

 * push more utility functions to common/
 * rename utility functions with error checking to x* as it is a more natural
   variation
