Get Cosmopolitan into releasable state

A new rollup tool now exists for flattening out the headers in a way
that works better for our purposes than cpp. A lot of the API clutter
has been removed. APIs that aren't a sure thing in terms of general
recommendation are now marked internal.

There's now a smoke test for the amalgamation archive and gigantic
header file. So we can now guarantee you can use this project on the
easiest difficulty setting without the gigantic repository.

A website is being created, which is currently a work in progress:
https://justine.storage.googleapis.com/cosmopolitan/index.html

libc/runtime/arch_prctl.c

@@ -165,7 +165,7 @@ int arch_prctl(int code, int64_t addr) {
   if (g_fsgs_once == 2) {
     return arch_prctl$fsgsbase(code, addr);
   }
-  switch (hostos) {
+  switch (__hostos) {
     case METAL:
       return arch_prctl$msr(code, addr);
     case FREEBSD: