Update to 0.52

Upstream changes:
0.52 2015.04.16
    The type of the Time::NVtime pointer is NV ()() not double ()(), as can be seen from looking at the Time::HiRes source.
      On Linux x86_64 on a uselongdouble build when you replace the Time::NVtime entry with a
      double (*)() pointer calls to that function end up leaving an entry on the FPU stack,
      eventually causing the failure seen at https://rt.perl.org/Ticket/Display.html?id=123879
      This minimal commit fixes that issue and allows DBIX::Class::TimeStamp to pass its tests.
      (Tony Cook)


(wen)