configure.ac: add --disable-gitversion

configure.ac: add --disable-gitversion

During development each git commit cause currently a complete
rebuild of the source tree. By passing --disable-gitversion to
configure we set a generic version string for ceph to prevent
getting after each commit a new version set.

remove src/check_version and replace with a extended version
of src/make_version which allows detecting changes in .git_version
and ceph_ver.h to avoid not needed updates.

This change also forces to call make_version each time to make
sure that changes from configure or the NO_VERSION env variable
are processed.

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>