Revert "cmake/pthread-config.cmake : use upstream FindThreads.cmake"
Revert "cmake/pthread-config.cmake : use upstream FindThreads.cmake"

This reverts commit 71878fbc22c222443dd222a832b365aa9d112d03.

Does not work if you have

project(foo CXX):

Make Error at /usr/share/cmake-2.8/Modules/CheckIncludeFiles.cmake:48
(TRY_COMPILE):
  Unknown extension ".c" for file

  /home/dmerewsky/work/qi/nao-flasher/build-sys-linux-x86_64/CMakeFiles/CMakeTmp/CheckIncludeFiles.c

  -- Looking for include files CMAKE_HAVE_PTHREAD_H - not found.
  try_compile() works only for enabled languages.  Currently these
  are:

  CXX

  See project() command to enable other languages.

And besides, it does not solve the gtest/pthread bug we were having ...

dmerejkowsky/qibuild,dmerejkowsky/qibuild,aldebaran/qibuild,dmerejkowsky/qibuild,dmerejkowsky/qibuild,dmerejkowsky/qibuild,aldebaran/qibuild,aldebaran/qibuild,aldebaran/qibuild