* CONTRIBUTE: improve; add explicit web references, move some info from
admin/notes/* here.
* INSTALL.REPO: You can't "just run make" after a clean checkout.
* admin/notes/commits: deleted; merged into ./CONTRIBUTE
* admin/notes/repo: move commit, branch info into ./CONTRIBUTE
* INSTALL: Prefer './configure FOO=BAR' to 'FOO=BAR ./configure'.
* INSTALL.REPO: pkg-config is no longer required to build from
the repository.
* autogen.sh: Don't check for pkg-config.
(progs): Remove pkg-config.
(pkg_config_min, AUTORECONF_ENV, env_space, ACLOCAL_PATH):
Remove. All uses removed.
* m4/pkg.m4: New file, built by admin/merge-pkg-config.
* configure.ac: Remove unnecessary m4_pattern_forbid of ^PKG_ and
an AC_ARG_VAR of PKG_CONFIG_PATH. pkg.m4 does that for us.
(EMACS_CHECK_MODULES): Remove workaround for old pkg-config bug,
as we use pkg.m4 from a newer pkg-config.
* admin/merge-pkg-config: New script.
* admin/notes/copyright: Update for m4/*.m4, in particular m4/pkg.m4.
* etc/NEWS: Prefer './configure FOO=BAR' to 'FOO=BAR ./configure'.
* etc/PROBLEMS (Build-time-problems): Remove pkg-config problem
that is no longer an issue.
* nt/INSTALL: Remove no-longer-needed notes about pkg-config.
* configure.ac: Use pkg-config's pkg.m4, rather than reinventing it.
Add explicit AC_SUBST's where needed.
* autogen.sh (progs): Add pkg-config.
(pkg_config_min): New variable.
* INSTALL.REPO: Mention pkg-config.
* etc/PROBLEMS: Mention a related issue that can occur with a local automake.
(ORDINARY_GOALS): New macro, which excludes 'bootstrap'.
(bootstrap, .PHONY): New rules.
* INSTALL.REPO: Document current procedure better.
Move copyright notice to just before license notice.