Switch from locally generated git tarball to official one.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

The current procps-ng Makefile calls the shipped autogen.sh script which
introduces incorrect implicit dependencies on host utilities, leading to
the following error observed on a minimal build system:

    (cd .../procps-ng-3.3.11; echo "3.3.11" > ".../procps-ng-3.3.11/.tarball-version"; ./autogen.sh );
    You must have autopoint installed to generate procps-ng build system.
    The autopoint command is part of the GNU gettext package.
    Makefile:96: recipe for target '.../procps-ng-3.3.11/.configured_yynyyyyy' failed
    make[3]: *** [.../procps-ng-3.3.11/.configured_yynyyyyy] Error 1

Apply the following changes in order to fix compilation:

 - Apply the generic autoreconf fixup to generate configure and Makefiles
 - Use Build/Prepare to populate .tarball-version and revert Build/Configure
   to its default implementation
 - Disable to build of docs and tests as those require additional utilities
   not guaranteed to be present

Fixes #2890.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>