hdf5

Merge pull request #2623 in HDFFV/hdf5 from ~LRKNOX/hdf5_lrk:develop to develop

* commit 'c7626f79fdee4eee13925e240ef41e61f3367eab':
  Add flags from config/clang-warnings/*general files to H5 C and CXX flags for all versions of Clang and Clang++ compilers. Switched from cut to awk in testcheck_version.sh.in to avoid dependence on tab vs. " " in version definitions in H5public.h.
  Add files for adding warning flags for clang compilers in autotools configure.