Have autogen.sh copy in some files

Debian policy calls for these files not to be duplicated. However, we
need to do it in a portable way (e.g., works on RPM-based systems so
/usr/share/misc/config.guess is not OK; does not touch network, so doing
curl/wget of the canonical config.guess file is not OK)

While there should be an obvious way to copy these files, there's .. not.
This is the best I could come up with, using files from automake without
actually invoking it.

While I did not actually BUILD on an rpm-based system, I checked the
content of the automake rpm of fedora 36 and it looks like it should work.

I'd rather avoid the new build-time dependency on automake, but
"automake --print-libdir" was the only 'portable' way I found to print
the location of a directory containing config.guess, config.sub and
install-sh.

Alternative to #1625

Author: jepler

debian/control.top.in

@@ -11,6 +11,7 @@ Build-Depends:
     @MODUTILS_DEPENDS@,
     @EXTRA_BUILD@,
     autoconf,
+    automake,
     bwidget (>= 1.7),
     desktop-file-utils,
     gettext,

src/.gitignore

@@ -3,9 +3,12 @@
 /.tmp_versions
 /Makefile.inc
 /Makefile.modinc
+/config.guess
 /config.h
 /config.log
 /config.status
+/config.sub
+/install-sh
 /objects
 /depends
 /autom4te.cache

src/autogen.sh

@@ -3,8 +3,22 @@ rm -rf autom4te.cache
 AUTOGEN_TARGET=${AUTOGEN_TARGET-configure:config.h.in}
 set -e
 case :$AUTOGEN_TARGET: in
-*:configure:*) autoconf; touch configure ;;
+*:configure:*)
+    automake_libdir=`automake --print-libdir`
+    [ -e config.guess ] || cp $automake_libdir/config.guess .
+    [ -e config.sub ] || cp $automake_libdir/config.sub .
+    [ -e install-sh ] || cp $automake_libdir/install-sh .
+    autoconf
+    # autoconf only updates the timestamp if the output actually changed.
+    # The target's timestamp must be updated or make is confused
+    touch configure
+    ;;
 esac
 case :$AUTOGEN_TARGET: in
-*:config.h.in:*) autoheader; touch config.h.in ;;
+*:config.h.in:*)
+    autoheader
+    # autoheader only updates the timestamp if the output actually changed.
+    # The target's timestamp must be updated or make is confused
+    touch config.h.in
+    ;;
 esac