any -j flags. (And their implied disabling of backwards compatibility,
which is the real cause of the make disttest failure).
p4raw-id: //depot/perl@26499
# 'make disttest' sets a bunch of environment variables which interfere
# with our testing.
-delete @ENV{qw(PREFIX LIB MAKEFLAGS)};
+delete @ENV{qw(PREFIX LIB MAKEFLAGS MAKE_JOBS_FIFO)};
my $perl = which_perl();
my $Is_VMS = $^O eq 'VMS';