Robustify build of autoconf by avoiding manpage generation.

* touch manpages to avoid (re-)generation during build, which won't
  work due to help2man not being available

sys-devel/autoconf/autoconf-2.69.recipe

@@ -5,7 +5,7 @@ DESCRIPTION="
 	because the person building the package is allowed to specify various
 	configuration options.
 	"
-HOMEPAGE="http://www.gnu.org/software/autoconf/" 
+HOMEPAGE="http://www.gnu.org/software/autoconf/"
 COPYRIGHT="1992-2012 Free Software Foundation, Inc."
 LICENSE="
 	GNU GPL v2
@@ -52,6 +52,11 @@ SOURCE_DIR="$portVersionedName"
 BUILD()
 {
 	autoreconf
+
+	# make sure that the build system doesn't try to update the manpages,
+	# as that requires help2man, which isn't available
+	touch man/*.1
+
 	PERL="perl" M4="m4" SED="sed" \
 		runConfigure ./configure
 	make $jobArgs