configure: Add --with-pkg{data,sysconf,libexec}dir options

Quick hack for discussion.

Makefile.in

@@ -21,11 +21,12 @@ srcdir	= @srcdir@
 libdir	= @libdir@
 incdir	= @includedir@
 mandir	= @mandir@
-datadir = @datarootdir@/@PACKAGE_NAME@
-sysconfdir=@sysconfdir@
-pkgconfdir=@sysconfdir@/@PACKAGE_NAME@
-libexecdir=@libexecdir@
-pkglibexecdir=@libexecdir@/@PACKAGE_NAME@
+datadir = @datadir@
+pkgdatadir = @pkgdatadir@
+sysconfdir = @sysconfdir@
+pkgsysconfdir = @pkgsysconfdir@
+libexecdir = @libexecdir@
+pkglibexecdir = @pkglibexecdir@
 SLINK	= @LN_S@
 STRIP	= @STRIP@
 ifdef SPARSE
@@ -68,8 +69,8 @@ ALL_CFLAGS = $(CFLAGS) --std=gnu99 -Wall $(COVERAGE_CFLAGS)
 DEBUG_CPPFLAGS ?= -DDEBUG
 ALL_CPPFLAGS = $(CPPFLAGS)			\
 	$(DEBUG_CPPFLAGS)			\
-	-DDATADIR=\"$(datadir)\"		\
-	-DPKGCONFDIR=\"$(pkgconfdir)\"		\
+	-DDATADIR=\"$(pkgdatadir)\"		\
+	-DPKGCONFDIR=\"$(pkgsysconfdir)\"	\
 	-DPKGLIBEXECDIR=\"$(pkglibexecdir)\"
 
 include $(srcdir)/source.mak
@@ -107,15 +108,15 @@ EMAN	= $(ETAGS_PROG).$(manext)
 #
 # corpora files
 #
-corporadir = $(datadir)/corpora
-pkgconf_corporadir = $(pkgconfdir)/corpora
+corporadir = $(pkgdatadir)/corpora
+pkgconf_corporadir = $(pkgsysconfdir)/corpora
 CORPORA    = ctags.ctags RFC1213-MIB.txt
 
 #
 # preload
 #
-preloaddir = $(datadir)/preload
-pkgconf_preloaddir = $(pkgconfdir)/preload
+preloaddir = $(pkgdatadir)/preload
+pkgconf_preloaddir = $(pkgsysconfdir)/preload
 PRELOAD_OPTLIB =				\
 	\
 	coffee.ctags				\
@@ -130,8 +131,8 @@ DEFAULT_PRELOAD_FILE=default.ctags
 #
 # config files
 #
-optlibdir = $(datadir)/optlib
-pkgconf_optlibdir = $(pkgconfdir)/optlib
+optlibdir = $(pkgdatadir)/optlib
+pkgconf_optlibdir = $(pkgsysconfdir)/optlib
 OPTLIB    = $(PRELOAD_OPTLIB)
 
 #
@@ -317,8 +318,8 @@ uninstall-etags:
 	- rm -f $(DEST_ETAGS) $(DEST_EMAN)
 
 uninstall-data: uninstall-corpora uninstall-optlib uninstall-preload
-	- rmdir $(datadir)
-	- rmdir $(pkgconfdir)
+	- rmdir $(pkgdatadir)
+	- rmdir $(pkgsysconfdir)
 
 uninstall-corpora:
 	- rm -f $(addprefix $(corporadir)/,$(CORPORA))

configure.ac

@@ -204,6 +204,18 @@ AC_ARG_ENABLE(tmpdir,
 		[default directory for temporary files [ARG=/tmp]])],
 	tmpdir_specified=yes)
 
+AC_ARG_WITH([pkgdatadir],
+	[AS_HELP_STRING([--with-pkgdatadir=DIR],
+		[ctags read-only architecture-independent data [DATADIR/ctags]])])
+
+AC_ARG_WITH([pkgsysconfdir],
+	[AS_HELP_STRING([--with-pkgsysconfdir=DIR],
+		[ctags read-only single-machine data [SYSCONFDIR/ctags]])])
+
+AC_ARG_WITH([pkglibexecdir],
+	[AS_HELP_STRING([--with-pkglibexecdir=DIR],
+		[ctags program executables [LIBEXECDIR/ctags]])])
+
 AC_ARG_PROGRAM
 
 # Process configuration options
@@ -213,6 +225,30 @@ if test "$enable_maintainer_mode" = yes ; then
 	AC_MSG_NOTICE(enabling maintainer mode)
 fi
 
+
+case "${with_pkgdatadir+set}"-"$with_pkgdatadir" in #(
+"set"-"yes" | "set"-"no") pkgdatadir="${datadir}/ctags"	  ;; #(
+"set"-*)		  pkgdatadir="${with_pkgdatadir}" ;; #(
+*)			  pkgdatadir="${datadir}/ctags"	  ;;
+esac
+
+case "${with_pkgsysconfdir+set}"-"$with_pkgsysconfdir" in #(
+"set"-"yes" | "set"-"no") pkgsysconfdir="${sysconfdir}/ctags"	;; #(
+"set"-*)		  pkgsysconfdir="${with_pkgsysconfdir}" ;; #(
+*)			  pkgsysconfdir="${sysconfdir}/ctags"	;;
+esac
+
+case "${with_pkglibexecdir+set}"-"$with_pkglibexecdir" in #(
+"set"-"yes" | "set"-"no") pkglibexecdir="${libexecdir}/ctags"	;; #(
+"set"-*)		  pkglibexecdir="${with_pkglibexecdir}" ;; #(
+*)			  pkglibexecdir="${libexecdir}/ctags"	;;
+esac
+
+AC_SUBST([pkgdatadir])
+AC_SUBST([pkgsysconfdir])
+AC_SUBST([pkglibexecdir])
+
+
 install_targets="install-ctags install-data install-libexec"
 AC_MSG_CHECKING(whether to install link to etags)
 if test yes = "$enable_etags"; then