Add reachover Makefiles for contrib/netbsd-tests/lib/libc; this adds approximately
500 new testcases

Various TODOs have been sprinkled around the Makefiles for items that even need
to be ported (missing features), testcases have issues with building/linking, or
issues at runtime.

A variant of this code has been tested extensively on amd64 and i386
10-STABLE/11-CURRENT for several months without issue. It builds on other
architectures, but the code will remain off until I have prove it works on
virtual hardware or real hardware on other architectures

In collaboration with: pho, Casey Peel <casey.peel@isilon.com>
Sponsored by: EMC / Isilon Storage Division
Improve the ability to cancel an in-flight request by using an
interrupt, via SIGCONT, to force the read or write system call to
return prematurely.

Reviewed by:	grehan