Greatly expand system() shell code features

The cosmopolitan command interpreter now has 13 builtin commands,
variable support, support for ; / && / || syntax, asynchronous support,
and plenty of unit tests with bug fixes.

This change fixes a bug in posix_spawn() with null envp arg. strace
logging now uses atomic writes for scatter functions. Breaking change
renaming GetCpuCount() to _getcpucount(). TurfWar is now updated to use
the new token bucket algorithm. WIN32 affinity masks now inherit across
fork() and execve().

libc/fmt/strtol.c

@@ -45,6 +45,8 @@
  *     on the the prefixes 0 (octal), 0x (hexadecimal), 0b (binary), or
  *     decimal (base 10) by default
  * @return the decoded signed saturated number
+ * @raise EINVAL if `base` isn't 0 or 2..36
+ * @raise ERANGE on overflow
  */
 long strtol(const char *s, char **endptr, int base) {
   char t = 0;