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/str/locale.h

@@ -78,6 +78,7 @@ wint_t towlower_l(wint_t, locale_t);
 wint_t towupper_l(wint_t, locale_t);
 int strcasecmp_l(const char *, const char *, locale_t);
 int strncasecmp_l(const char *, const char *, size_t, locale_t);
+ssize_t strfmon_l(char *, size_t, locale_t, const char *, ...);
 
 COSMOPOLITAN_C_END_
 #endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */

libc/str/str.h

@@ -151,6 +151,7 @@ wchar_t *wmempcpy(wchar_t *, const wchar_t *, size_t) memcpyesque;
 wchar_t *wmemmove(wchar_t *, const wchar_t *, size_t) memcpyesque;
 void *tinymemccpy(void *, const void *, int, size_t) memcpyesque;
 void *memmem(const void *, size_t, const void *, size_t) libcesque nosideeffect;
+ssize_t strfmon(char *, size_t, const char *, ...);
 long a64l(const char *);
 char *l64a(long);
 

libc/str/strchr.c

@@ -61,6 +61,7 @@ noasan static inline const char *strchr_sse(const char *s, unsigned char c) {
  * @return pointer to first instance of c or NULL if not found
  *     noting that if c is NUL we return pointer to terminator
  * @asyncsignalsafe
+ * @vforksafe
  */
 char *strchr(const char *s, int c) {
   const char *r;

libc/str/strncpy.c

@@ -60,6 +60,7 @@
  * @return dest
  * @see stpncpy(), memccpy()
  * @asyncsignalsafe
+ * @vforksafe
  */
 char *strncpy(char *dest, const char *src, size_t stride) {
   size_t i;