Cygwin: implement extensible clock interface

- Drop hires_[nm]s clocks, rename hires.h to clock.h.

- Implement clk_t class as an extensible clock class in new file clock.cc.

- Introduce get_clock(clock_id) returning a pointer to the clk_t instance
  for clock_id.  Provide the following methods along the lines of the former
  hires classes:

	void		clk_t::nsecs (struct timespec *);
	ULONGLONG	clk_t::nsecs ();
	LONGLONG	clk_t::usecs ();
	LONGLONG	clk_t::msecs ();
	void 		clk_t::resolution (struct timespec *);

- Add CLOCK_REALTIME_COARSE, CLOCK_MONOTONIC_RAW, CLOCK_MONOTONIC_COARSE
  and CLOCK_BOOTTIME clocks.

- Allow clock_nanosleep, pthread_condattr_setclock and timer_create to use
  all new clocks (both clocks should be usable with a small tweak, though).

- Bump DLL major version to 2.12.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

winsup/cygwin/autoload.cc

@@ -586,6 +586,14 @@ LoadDLLfunc (GetSystemTimePreciseAsFileTime, 4, kernel32)
 LoadDLLfuncEx (PrefetchVirtualMemory, 16, kernel32, 1)
 LoadDLLfunc (SetThreadGroupAffinity, 12, kernel32)
 
+/* MSDN claims these are exported by kernel32.dll, but only
+   QueryUnbiasedInterruptTime actually is.  The others are only
+   available via KernelBase.dll. */
+LoadDLLfunc (QueryInterruptTime, 4, KernelBase)
+LoadDLLfunc (QueryInterruptTimePrecise, 4, KernelBase)
+LoadDLLfunc (QueryUnbiasedInterruptTime, 4, KernelBase)
+LoadDLLfunc (QueryUnbiasedInterruptTimePrecise, 4, KernelBase)
+
 /* ldap functions are cdecl! */
 #pragma push_macro ("mangle")
 #undef mangle