Generate admin/charsets Makefile via configure, and make more portable.

Generate admin/charsets Makefile via configure, and make more portable.

* configure.ac (SUBDIR_MAKEFILES): Add admin/charsets/Makefile.
(admin/charsets/Makefile): Generate it.
* admin/charsets/Makefile.in: Rename from Makefile.
(AWK, srcdir, top_srcdir, AM_DEFAULT_VERBOSITY):
New variables, set by configure.
(charsetdir, lispintdir, mapfiledir, AM_V_GEN, am__v_GEN_)
(am__v_GEN_0, am__v_GEN_1, AM_V_at, am__v_at_, am__v_at_0)
(am__v_at_1, LOCAL, mapconv, run_mapconv, big5, compact, cp51932)
(cp932, eucjp_ms, gb180302, gb180304, kuten): New variables.
(TRANS_TABLE, CHARSETS): Add directory prefix to value.
(all): Declare PHONY.
(local): New PHONY target.
(map_template): New template.  Use to define short PHONY aliases.
(*.map): Add directory prefixes to targets and prerequisites.
Respect make verbosity.
(JISC6226.map): Replace non-portable sed append without newline.
(install): Remove rule.
(clean): Only delete temporary sedscript.
(bootstrap-clean, distclean, maintainer-clean, extraclean)
(totalclean): New PHONY rules.
* admin/charsets/mapconv (BASE): Replace basename with expr.
(FILE): Add "mapfiles" subdirectory.
(AWK): New variable.  Use throughout in place of "awk".
(main): Use "gunzip -c" in place of "zcat".
Don't leave whitespace before "p", for older sed.
* admin/charsets/mapfiles/PTCP154: Add final newline,
to make older sed versions happy.
; * .gitignore: Ignore admin/charsets/Makefile.