Fix small matters and improve sysconf()

- Fix mkdeps.com out of memory error
- Remove static memory from __get_cpu_count()
- Add support for passing hyphen to cat in cocmd
- Change more ZipOS errors from ENOTSUP to EROFS
- Specify mem_unit in sysinfo() output on BSD OSes

libc/calls/fchmod.c

@@ -29,6 +29,6 @@
  * @see chmod()
  */
 int fchmod(int fd, uint32_t mode) {
-  /* TODO(jart): Windows */
+  // TODO(jart): Windows
   return sys_fchmod(fd, mode);
 }