RFR: 8194860: Cleanup Semaphore timed-wait time calculations

[David Holmes]

bug: https://bugs.openjdk.java.net/browse/JDK-8194860
webrev: http://cr.openjdk.java.net/~dholmes/8194860/webrev/

Details in the bug report, but there was duplication in functionality 
with regards to timeout conversions/calculations, and the os_bsd.cpp 
code was broken due to OSXSemaphore and PosixSemaphore having different 
API's.

Summary:
- expanded the API to take a relative timeout in millis as well as the 
existing absolute timeout as a timespec:

   // wait until the given absolute time is reached
   bool timedwait(struct timespec ts);
   // wait until the given relative time elapses
   bool timedwait(int64_t millis);

The millis version simply converts to a timespec and calls the other 
version e.g

bool PosixSemaphore::timedwait(int64_t millis) {
   struct timespec ts;
   os::Posix::to_RTC_abstime(&ts, millis);
   return timedwait(ts);
}

- added os::Posix::to_RTC_abstime to do the relative to absolute 
conversion using the existing routines in os::Posix used for 
PlatformEvent etc.

- changed callsites to use new millis version

- I had to rearrange the ifndef SOLARIS in os_posix.cpp to expose 
previously hidden code to Solaris. It isn't all needed by Solaris but I 
chose not to clutter things with too many ifdefs and only excluded 
things that really shouldn't be done on Solaris. Also needed to call 
os::Posix::init on Solaris.

Testing (still in progress):
- mach 5 tiers 1 - 3 (Linux, Solaris, OS X, Windows)
- test/jdk/jdk/jfr (as suspend/resume is the user of the semaphore code)

Thanks,
David