Fix for perl 5.26.0+ (no . in @inc by default)
Index: Makefile.PL
--- Makefile.PL.orig
+++ Makefile.PL
@@ -1,3 +1,4 @@
+BEGIN { push @INC, '.'; }
 use inc::Module::Install;
 
 all_from 'lib/Parallel/Prefork.pm';