Merge branch 'win32-fixes'

This patchset fixes win32 builds after some previous patches (referenced
in particular commits), and also removes some quirks for win32.

* win32-fixes:
  test: do not return void
  log/win32: fix exporting extern variable
  log-internal: missing extern "C"
  log: remove USE_GLOBAL_FOR_DEBUG_LOGGING
  cmake: Export missing symbols for win32
  cmake: eliminate EVENT_BUILDING_REGRESS_TEST, since we link with shared libs
  test: windows doesn't have WNOWAIT
  cmake: clean not used #defines from event-config.h
  cmake: add <pthread.h> only for non-win32