* Two routines (oct_nanosleep and get_memory_usage) in oct_f.c contained #ifdef linux. This was presumably due to a concern that routines inside that part might not exist on other platforms. The more appropriate procedure is just to check whether the desired routines (nanosleep, sysconf, getpid) are available, which we are already doing in the configure script for other routines. These are all available on MacOS, for example, so it is unnecessarily restrictive to disable usage if not Linux.
* Documentation and clearer name for (l)oct_nanosleep arguments. I think they were copied by false analogy from gettimeofday: there usec means microseconds, but here it is nanoseconds.
* oct_nanosleep can just pass NULL for the rem argument, since we are not going to use the possible return value there anyway.