* hires.h (hires_ms::minperiod): Remove static designation.
(hires::began_period): New field.
* signal.cc: Include headers required for cygheap.h now that gtod lives in the
cygheap.
* timer.c: Ditto.
* times.cc (gtod): Delete variable.
(gtod::minperiod): Ditto.
(gtod::began_period): Define.
(hires_ms::prime): Add more debugging output. Call timeBeginPeriod only when
!began_period.