Remove dependency to help2man, which tries to regenerate the manpages.
As the failure to use help2man has become an error with automake-1.13,
we just use the manpages that come with the source.

diff -ruwN libtool-2.4/Makefile.am libtool-2.4_haiku/Makefile.am
--- libtool-2.4/Makefile.am	2010-09-21 09:07:22.038535168 +0200
+++ libtool-2.4_haiku/Makefile.am	2013-04-23 23:41:18.886833152 +0200
@@ -322,16 +322,6 @@
 	  $(MAKEINFO) --no-headers $(MAKEINFOFLAGS) -o notes.txt notes.texi
 
 dist_man1_MANS		= $(srcdir)/doc/libtool.1 $(srcdir)/doc/libtoolize.1
-MAINTAINERCLEANFILES	+= $(dist_man1_MANS)
-update_mans = \
-  PATH=.$(PATH_SEPARATOR)$$PATH; export PATH; \
-  $(HELP2MAN) --output=$@
-$(srcdir)/doc/libtool.1: $(srcdir)/$(auxdir)/ltmain.sh
-	$(update_mans) --help-option=--help-all libtool
-$(srcdir)/doc/libtoolize.1: $(srcdir)/libtoolize.in
-	$(update_mans) libtoolize
-
-
 ## ------------- ##
 ## Installation. ##
 ## ------------- ##