Undiamond Python headers

This change gets the Python codebase into a state where it conforms to
the conventions of this codebase. It's now possible to include headers
from Python, without worrying about ordering. Python has traditionally
solved that problem by "diamonding" everything in Python.h, but that's
problematic since it means any change to any Python header invalidates
all the build artifacts. Lastly it makes tooling not work. Since it is
hard to explain to Emacs when I press C-c C-h to add an import line it
shouldn't add the header that actually defines the symbol, and instead
do follow the nonstandard Python convention.

Progress has been made on letting Python load source code from the zip
executable structure via the standard C library APIs. System calss now
recognizes zip!FILENAME alternative URIs as equivalent to zip:FILENAME
since Python uses colon as its delimiter.

Some progress has been made on embedding the notice license terms into
the Python object code. This is easier said than done since Python has
an extremely complicated ownership story.

- Some termios APIs have been added
- Implement rewinddir() dirstream API
- GetCpuCount() API added to Cosmopolitan Libc
- More bugs in Cosmopolitan Libc have been fixed
- zipobj.com now has flags for mangling the path
- Fixed bug a priori with sendfile() on certain BSDs
- Polyfill F_DUPFD and F_DUPFD_CLOEXEC across platforms
- FIOCLEX / FIONCLEX now polyfilled for fast O_CLOEXEC changes
- APE now supports a hybrid solution to no-self-modify for builds
- Many BSD-only magnums added, e.g. O_SEARCH, O_SHLOCK, SF_NODISKIO

libc/runtime/sysconf.c

@@ -27,13 +27,15 @@
  * - `_SC_CLK_TCK` returns number of clock ticks per second
  * - `_SC_ARG_MAX` currently always returns 32768 due to Windows
  * - `_SC_PAGESIZE` currently always returns 65536 due to Windows
+ * - `_SC_NPROCESSORS_ONLN` returns number of CPUs in the system
  *
- * You are encouraged to undiamond calls to this API as follows:
+ * Some suggestions:
  *
- * - Use `CLK_TCK` instead of `getconf(_SC_CLK_TCK)`
+ * - `CLK_TCK` should be favored over `getconf(_SC_CLK_TCK)`
  * - Use `PAGESIZE` or `FRAMESIZE` instead of `getconf(_SC_PAGESIZE)`
  */
 long sysconf(int name) {
+  int n;
   switch (name) {
     case _SC_ARG_MAX:
       return ARG_MAX;
@@ -41,6 +43,9 @@ long sysconf(int name) {
       return CLK_TCK;
     case _SC_PAGESIZE:
       return FRAMESIZE;
+    case _SC_NPROCESSORS_ONLN:
+      n = GetCpuCount();
+      return n > 0 ? n : -1;
     default:
       return -1;
   }