Merge branch 'main' of ssh://git.rileyk.au:19482/riley/uniproc

Added function to check if all processes are finished without blocking
Added a function to set a uniproc_process object to a known invalid value
Added a function to check if a process is a known invalid value
Added userdata variable to struct as well as functions to set/get it

AMEND: Updated uniproc_close_process to set the process to a known invalid value
All functions now ignore uniproc_process's with a known invalid value
uniproc_create_process will now return a known invalid value if it fails to create a process

src/uniproc_unix.c

@@ -117,6 +117,7 @@ void uniproc_close_process(uniproc_process* p)
 	fclose(p->in);
 	fclose(p->out);
 	fclose(p->err);
+	uniproc_nullify_processes(p, 1);
 }
 
 bool uniproc_are_processes_finished(const uniproc_process* p, const size_t num_processes)

src/uniproc_win64.c

@@ -169,6 +169,7 @@ void uniproc_close_process(uniproc_process* p)
 	fclose(p->in);
 	fclose(p->out);
 	fclose(p->err);
+	uniproc_nullify_processes(p, 1);
 }
 
 bool uniproc_are_processes_finished(const uniproc_process* p, const size_t num_processes)