Resource leak when `subprocess_create_ex()` fails

[wn2000]

The subprocess_create_ex() function just has return -1 in case of an error, without properly closing already open file descriptors.

Example:

subprocess.h/subprocess.h

Lines 876 to 880 in 7e59b69

	if (0 != posix_spawnp(&child, commandLine[0], &actions, SUBPROCESS_NULL,
	(char *const *)commandLine, used_environment)) {
	posix_spawn_file_actions_destroy(&actions);
	return -1;
	}

In my test, trying to call this function with a non-existing command results in 6 more new FDs each time.

[starseeker]

The following is helpful (at least on Linux) for debugging this (see https://developers.redhat.com/articles/2023/01/09/how-use-valgrind-track-file-descriptors#valgrind___track_fds_yes):

valgrind -q --tool=none --track-fds=yes

[starseeker]

(Note - found out the hard way if you forget to call subprocess_destroy, fd leaks - even in normal usage - are one of the symptoms)

[sheredom]

Thanks for the report. Super busy at the moment but when I get the time I'll take a look!