POSIX says that ‘echo FOO’ produces implementation-defined output
if FOO contains leading ‘-’, or ‘\’ anywhere, so don’t assume GNU
behavior in that case.
* Makefile.in (removenullpaths): Remove.
(epaths-force): Rewrite to avoid the need for ‘echo’.
(install-etc): Be clearer about escaping the shell metacharacters
‘\’ and ‘$’.
* Makefile.in (install-arch-indep, install-etcdoc):
* admin/charsets/mapconv, admin/merge-gnulib, admin/merge-pkg-config:
* admin/quick-install-emacs, build-aux/gitlog-to-emacslog:
* configure.ac, lib-src/rcs2log, make-dist:
* src/Makefile.in (lisp.mk):
Don’t assume ‘echo’ outputs ‘\’ and leading ‘-’ unscathed.
For example, use ‘printf '%s\n' "$foo"’ rather than ‘echo "$foo"’
if $foo can contain arbitrary characters.
* lisp/Makefile.in (TAGS): Use ‘ls’, not ‘echo’, to avoid ‘\’ issues.
* doc/lispref/two-volume.make (vol1.pdf):
* test/etags/make-src/Makefile (web ftp publish):
Use ‘printf’ rather than ‘echo -e’.

Run admin/update-copyright.

* 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.