Makefile.inc1: Print the right PATH for missing install tool error

We override PATH for which but then go and print the non-overridden
PATH, which leads to rather confusing messages.

Fixes: 5bb9250e0af4 ("Add necessary Makefile.inc1 infrastructure for building on non-FreeBSD")
(cherry picked from commit 4ebd18cf357af71941675ff3ae7fb3bf56a37e0e)