Project: help  b07c31d8dfa44e18560eaacfe7f63ef2e5e23ff7

Replace usage of readlink -f with realpath.

For consistency reasons, the other scripts use the latter. Additionally on
macOS/BSD readlink -f option is not available, nor other default tools
for canonicalizing paths, so looking for GNU's realpath in the first
place is a better bet.

Change-Id: I77b82a956f63c66e352a372895cd623f83916168
Reviewed-on: https://gerrit.libreoffice.org/45486Reviewed-by: Olivier Hallot <olivier.hallot@libreoffice.org>
Tested-by: Olivier Hallot <olivier.hallot@libreoffice.org>