previous changes to this port was one of them. This commit fixes:
- We definetely need to check the existence of ${PREFIX}/dir and generate
it if needed before install-info gets invoked.
- Use empty definition of STRIP instead of changing every appearance
of ${INSTALL_SCRIPT} in Makefile.in to ${INSTALL} especially since
this port installs no files that need to be stripped.
- No need to add rule to regenerate .info file when there's one in the
distributed Makefile.in.
- Instead of removing old piece of .info files in post-install target,
leave it to the .texi.info: rule in the distributed Makefile.
