Make improvements

- You can now run `make -j8 toolchain` on Windows
- You can now run `make -j` on MacOS ARM64 and BSD OSes
- You can now use our Emacs dev environment on MacOS/Windows
- Fix bug where the x16 register was being corrupted by --ftrace
- The programs under build/bootstrap/ are updated as fat binaries
- The Makefile now explains how to download cosmocc-0.0.12 toolchain
- The build scripts under bin/ now support "cosmo" branded toolchains
- stat() now goes faster on Windows (shaves 100ms off `make` latency)
- Code cleanup and added review on the Windows signal checking code
- posix_spawnattr_setrlimit() now works around MacOS ARM64 bugs
- Landlock Make now favors posix_spawn() on non-Linux/OpenBSD
- posix_spawn() now has better --strace logging on Windows
- fstatat() can now avoid EACCES in more cases on Windows
- fchmod() can now change the readonly bit on Windows

libc/intrin/waitforsingleobject.c

@@ -18,6 +18,7 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/calls/syscall_support-nt.internal.h"
 #include "libc/intrin/strace.internal.h"
+#include "libc/nt/runtime.h"
 #include "libc/nt/synchronization.h"
 #include "libc/nt/thunk/msabi.h"
 
@@ -30,7 +31,7 @@ __msabi extern typeof(WaitForSingleObject) *const __imp_WaitForSingleObject;
 uint32_t WaitForSingleObject(int64_t hHandle, uint32_t dwMilliseconds) {
   uint32_t rc;
   rc = __imp_WaitForSingleObject(hHandle, dwMilliseconds);
-  POLLTRACE("WaitForSingleObject(%ld, %'d) → %d% m", hHandle, dwMilliseconds,
-            rc);
+  POLLTRACE("WaitForSingleObject(%ld, %'d) → %d %d", hHandle, dwMilliseconds,
+            rc, GetLastError());
   return rc;
 }