Change support vector to Windows 8+

Doing this makes binaries tinier, since we don't need to have all the
extra code for supporting a 32-bit address space. It also benefits us
because we're able to use WIN32 futexes, which makes locking simpler.

b69f3d2488 is what officially ended our
Windows 7 support. This change is merely a formalization. You can use
old versions of Cosmo now and forevermore if you need Windows 7 since
our repository is hermetic and vendors all its dependencies.

Won't fix #617

libc/nt/synchronization.h

@@ -54,6 +54,11 @@ typedef void (*NtTimerapcroutine)(void *lpArgToCompletionRoutine,
 typedef void (*NtWaitOrTimerCallback)(void *lpParameter,
                                       bool32 TimerOrWaitFired);
 
+void WakeByAddressAll(void *Address);
+void WakeByAddressSingle(void *Address);
+bool32 WaitOnAddress(volatile void *Address, void *CompareAddress,
+                     size_t AddressSize, uint32_t opt_dwMilliseconds);
+
 void Sleep(uint32_t dwMilliseconds);
 uint32_t SleepEx(uint32_t dwMilliseconds, bool32 bAlertable);