RT478: Add uninstall make target

Add INSTALLDIRS variable, list of directories where things get
installed. Change install_html_docs to use perl mkdir-p script.

Add uninstall, uninstall_sw, uninstall_docs, uninstall_html_docs
to Makefile.org.  The actions of these targets were figured out
by "inverting" the install target.

Recurse into subdirs to do uninstall as needed.  Added uninstall
targets whose actions were similarly figured out by "inverting"
the install target.

Also remove some 'space before tab' complaints in Makefile.org

Reviewed-by: Tim Hudson <tjh@openssl.org>