[tor-bugs] #20241 [Core Tor/Tor]: Fix compilation on osx sierra (10.12)

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#20241: Fix compilation on osx sierra (10.12)
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     Reporter:  nickm         |      Owner:
         Type:  defect        |     Status:  new
     Priority:  Medium        |  Milestone:  Tor: 0.2.8.x-final
    Component:  Core Tor/Tor  |    Version:
     Severity:  Normal        |   Keywords:  osx
Actual Points:                |  Parent ID:
       Points:                |   Reviewer:
      Sponsor:                |
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 OSX Sierra (which came out last week) broke compilation in two ways:

    * It added a getentropy() function, but only if you include
 sys/random.h (which nobody else seems to require).
    * It added clock_gettime(), but uses a wider type for tv_nsec than
 tv_usec (why? Where does apple run that provides an "int" that holds up to
 1e6, but where you need a "long" to hold 1e9??).
    * It added clock_gettime(), but didn't add pthread_condattr_setclock()
 (whereas everybody else supports neither or both).

 My branch `osx_sierra_028` fixes both.  I'm going to merge it to master as
 low-risk so I can keep doing development, and ask for review on getting it
 into 028.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/20241>
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