would grep everything out of @INC due to faulty logic.
haarg pointed out it'd be better to just quote -I arguments,
so that's what this commit is.
my %maybe_libs = map +($_ => 1), grep defined, (values %Config, '.');
-my @extra_libs = grep -e not(ref($_) or $maybe_libs{$_}), @INC;
-
-my $extra_libs = join '', map " -I$_\n", @extra_libs;
+my @extra_libs = grep not(ref($_) or $maybe_libs{$_}), @INC;
+my $extra_libs = join '', map {
+ my $lib = $_;
+ $lib =~ s{'}{'\\''}g;
+ " -I'$lib'\n";
+} @extra_libs;
my $command = qq(
$^X