Extra checks for PERL_PATH and SHELL_PATH?

Hi,

The top-level Makefile currently contains

ifndef SHELL_PATH
	SHELL_PATH = /bin/sh
endif
ifndef PERL_PATH
	PERL_PATH = /usr/bin/perl
endif

The checks are only necessary if these variables need to be overridden
by environment variables, not just via the make command line.  Is this
the case?

-- 
Matt Kraai                                           http://ftbfs.org/