bldchn, never use AC_INIT's version info
import git-version-gen, etc. from twstools v0.4.0-54-g5e023df
bldchn, generate version.mk at configure and make time
build version.c and libversion.a
bldchn, gengetopt files are using version.h
use uterus_version_string instead of PACKAGE_VERSION
bldchn, add missing links to libversion.a
bldchn, man pages depend on VERSION
bldchn, info pages depend on VERSION
bldchn, add do_subst function

We want to use this in future instead of AC_CONFIG_FILES to
enrich some files with an up-to-date VERSION.
bldchn, create .pc pkg-config files at make time
fix missing version links for DSO

problem if DSO also includes *.clo.c ...
Merge remote-tracking branch 'rudi/bld/git-version-gen' into next

* rudi/bld/git-version-gen:
  fix missing version links for DSO
  bldchn, create .pc pkg-config files at make time
  bldchn, add do_subst function
  bldchn, info pages depend on VERSION
  bldchn, man pages depend on VERSION
  bldchn, add missing links to libversion.a
  use uterus_version_string instead of PACKAGE_VERSION
  bldchn, gengetopt files are using version.h
  build version.c and libversion.a
  bldchn, generate version.mk at configure and make time
  import git-version-gen, etc. from twstools v0.4.0-54-g5e023df
  bldchn, never use AC_INIT's version info