Remove config.cache files when reconfiguring at top level

[Alfred M. Szmidt]

   *************** local-distclean:
   *** 771,776 ****
   --- 771,777 ----
	    -rmdir texinfo/doc texinfo/info texinfo/intl texinfo/lib 
   2>/dev/null
	    -rmdir texinfo/makeinfo texinfo/po texinfo/util 2>/dev/null
	    -rmdir fastjar gcc libiberty texinfo zlib 2>/dev/null
   +       -find . -name config.cache -exec rm -f {} \; 2>/dev/null

I'd use -delete instead of `rm -f {} \;'.  But I think this is OK too.

      local-maintainer-clean:
	    @echo "This command is intended for maintainers to use;"