Fix Fedora 34/35 issue where 'which' detection of 'which' wasn't working
because Fedora use alias and proc
Fixup of fca5ad55d2 prereq-build: fix `which` detection on Fedora
Reported-by: Jani Partanen <rtfm@iki.fi>
Suggest-by: Etienne Champetier <champetier.etienne@gmail.com>
Tested-by: Georgi Valkov <gvalkov@abv.bg>
Signed-off-by: Paul Spooren <mail@aparcar.org>