Fix XNU / FreeBSD / OpenBSD / RHEL5 / NT bugs

For the first time ever, all tests in this codebase now pass, when
run automatically on macos, freebsd, openbsd, rhel5, rhel7, alpine
and windows via the network using the runit and runitd build tools

- Fix vfork exec path etc.
- Add XNU opendir() support
- Add OpenBSD opendir() support
- Add Linux history to syscalls.sh
- Use copy_file_range on FreeBSD 13+
- Fix system calls with 7+ arguments
- Fix Windows with greater than 16 FDs
- Fix RUNIT.COM and RUNITD.COM flakiness
- Fix OpenBSD munmap() when files are mapped
- Fix long double so it's actually long on Windows
- Fix OpenBSD truncate() and ftruncate() thunk typo
- Let Windows fcntl() be used on socket files descriptors
- Fix Windows fstat() which had an accidental printf statement
- Fix RHEL5 CLOCK_MONOTONIC by not aliasing to CLOCK_MONOTONIC_RAW

This is wonderful. I never could have dreamed it would be possible
to get it working so well on so many platforms with tiny binaries.

Fixes #31
Fixes #25
Fixes #14

libc/nt/synchronization.h

@@ -50,6 +50,8 @@ COSMOPOLITAN_C_START_
 typedef void (*NtTimerapcroutine)(void *lpArgToCompletionRoutine,
                                   uint32_t dwTimerLowValue,
                                   uint32_t dwTimerHighValue);
+typedef void (*NtWaitOrTimerCallback)(void *lpParameter,
+                                      bool32 TimerOrWaitFired);
 
 void Sleep(uint32_t dwMilliseconds);
 uint32_t SleepEx(uint32_t dwMilliseconds, bool32 bAlertable);
@@ -68,6 +70,10 @@ uint32_t WaitForSingleObjectEx(int64_t hHandle, uint32_t dwMilliseconds,
 uint32_t WaitForMultipleObjectsEx(unsigned int nCount, const int64_t *lpHandles,
                                   bool32 bWaitAll, uint32_t dwMilliseconds,
                                   bool32 bAlertable);
+bool32 RegisterWaitForSingleObject(int64_t *phNewWaitObject, int64_t hObject,
+                                   NtWaitOrTimerCallback Callback,
+                                   void *Context, uint32_t dwMilliseconds,
+                                   uint32_t dwFlags);
 
 int64_t CreateWaitableTimer(struct NtSecurityAttributes *lpTimerAttributes,
                             bool32 bManualReset, const char16_t *lpTimerName);