strncpy -> rtapi_strlcpy for string termination

[smoe]

Stuttgart LinuxCNC attempt to address compiler warnings.

Using rtapi_strlcpy to always have 0-terminated strings.

[petterreinholdtsen]

"libnml/buffer/shmem.cc:318:10: error: ‘rtapi_strlcpy’ was not declared in this scope"

Missing include file?

[gmoccapy]

linuxcnc stuttgart meeting (norbert not to blame) says merge when CI passes. eventually convert to std::string.

[petterreinholdtsen]

The std::string proposal came up in #1922 too. How can we decide if we want to move towards std::string or not?

[smoe]

Some tests are failing:

Running test: ./tests/twopass-personality
Running test: ./tests/twopass
Running test: ./tests/uspace/spawnv-root
Runtest: 259 tests run, 257 successful, 2 failed + 0 expected, 1 skipped
Failed: 
	./tests/motion-logger/mountaindew
	./tests/remap/remap-io

Let's see if that also happens for other PRs or if I have indeed messed something up.

[petterreinholdtsen]

I rebased the change on top of the 2.9 branch, and did some minor cleanup.

…

-- Happy hacking Petter Reinholdtsen