Update the Haikuporter install script (installhaikuporter.sh) so that if it doesn't detect finddir or installoptionalpackage that it will display a message to the user and politely exit.  Currently if you try to run it on linux you might get something like this:

wget http://ports.haiku-files.org/svn/haikuporter/trunk/installhaikuporter.sh -O- -q | sh -
sh: line 4: finddir: command not found
sh: line 4: notify: command not found
sh: line 13: finddir: command not found
sh: line 4: finddir: command not found
sh: line 4: notify: command not found
sh: line 15: installoptionalpackage: command not found
sh: line 4: finddir: command not found
sh: line 4: notify: command not found
sh: line 19: finddir: command not found
svn: Working copy 'haikuporter' locked
svn: run 'svn cleanup' to remove locks (type 'svn help cleanup' for details)
sh: line 4: finddir: command not found
sh: line 4: notify: command not found
sh: line 23: finddir: command not found
sh: line 23: cd: /haikuporter: Not a directory
sh: line 24: finddir: command not found
cp: omitting directory `haikuporter'
sh: line 27: finddir: command not found
sh: line 28: finddir: command not found
cp: cannot create regular file `/haikuports.conf': Permission denied
sh: line 4: finddir: command not found
sh: line 4: notify: command not found
sh: line 31: finddir: command not found
sh: line 4: finddir: command not found
sh: line 4: notify: command not found
sh: line 33: installoptionalpackage: command not found
sh: line 4: finddir: command not found
sh: line 4: notify: command not found
sh: line 37: haikuporter: command not found
sh: line 4: finddir: command not found
sh: line 4: notify: command not found
sh: line 40: haikuporter: command not found
sh: line 4: finddir: command not found
sh: line 4: notify: command not found

This task it to update installhaikuporter.sh so that it presents a more friendly response when executed on a non-Haiku system.