doc: clone+build instructions

* README-hacking: New file.
* bootstrap: Remove obsolete comments.

README-hacking

+-*- outline -*-
+
+These notes intend to help people working on the checked-out sources.
+These requirements do not apply when building from a distribution tarball.
+See also HACKING for more detailed libvirt contribution guidelines.
+
+* Requirements
+
+We've opted to keep only the highest-level sources in the GIT repository.
+This eases our maintenance burden, (fewer merges etc.), but imposes more
+requirements on anyone wishing to build from the just-checked-out sources.
+Note the requirements to build the released archive are much less and
+are just the requirements of the standard ./configure && make procedure.
+Specific development tools and versions will be checked for and listed by
+the bootstrap script.  See README-prereq for specific notes on obtaining
+these prerequisite tools.
+
+Valgrind <http://valgrind.org/> is also highly recommended, if
+Valgrind supports your architecture. See also README-valgrind.
+
+While building from a just-cloned source tree may require installing a
+few prerequisites, later, a plain `git pull && make' should be sufficient.
+
+* First GIT checkout
+
+You can get a copy of the source repository like this:
+
+        $ git clone git://libvirt.org/libvirt
+        $ cd libvirt
+
+The next step is to get and check other files needed to build,
+which are extracted from other source packages:
+
+        $ ./bootstrap
+
+Then run this to create e.g., Makefiles and ./configure,
+and to invoke ./configure:
+
+        $ ./autogen.sh
+
+And there you are!  Just
+
+        $ make
+        $ make check
+
+At this point, there should be no difference between your local copy,
+and the GIT master copy:
+
+        $ git diff
+
+should output no difference.
+
+Enjoy!
+
+Local Variables:
+indent-tabs-mode: nil
+End:

bootstrap

 #!/bin/sh
-# Run this after autogen.sh, to pull in all of the gnulib-related bits.
-# It's important to run *after* autogen.sh, since it updates some of
-# the same files autogen.sh does, yet those from gnulib are newer,
-# and match the tests.  So if a gnulib bug has been fixed since the
-# snapshot taken for whatever gettext release you're using, yet you
-# run "make check" against the wrong version, the corresponding unit
-# test in gl-tests/ may well fail.
+# Run this before autogen.sh, to pull in all of the gnulib-related bits.
 
 usage() {
   echo >&2 "\