Always set arguments on POSIX

[amerry]

Explicitly specifying an executable (either with boost::filesystem::path
or boost::process::exe) and no arguments causes NULL to be passed as the
argument list.

Not only is this unexpected behaviour for the child process (which
doesn't even have argv[0]), it is not portable across UNIX systems. From
the execve(2) man page on Linux:

"On Linux, either argv or envp can be specified as NULL, which has the
same effect as specifying these arguments as a pointer to a list
containing a single NULL pointer. Do not take advantage of this
misfeature! It is nonstandard and nonportable: on most other UNIX
systems doing this will result in an error (EFAULT)."

[klemens-morgenstern]

TBH I'd feel more comfortable if you would put your own name in as copyright holder to be honest. It looks a bit strange to have a company in an open-source library.

[amerry]

It's inaccurate, though - I don't own the copyright on this work (although I do have permission from my employer to make these and similar contributions). Note that other parts of the Boost codebase have copyrights by Microsoft, Multi Media Ltd, Garmin Ltd and Cadenza New Zealand Ltd, among others.

If I was doing this on my own time, it would be different (I have a release from my employer for that), but this is done on company time to support company software.

Although I'm pretty sure exit_argc.cpp isn't copyrightable in most jurisdictions anyway...