Search in /usr/share/openmortal/script rather than relying on the (very)
old behaviour of @INC including '.'.

https://bugs.gentoo.org/979367
--- a/src/Backend.cpp
+++ b/src/Backend.cpp
@@ -163,7 +163,7 @@ bool Backend::Construct()
 	
 //	char *perl_argv[] = {"", "-d:Trace", "Backend.pl"};
 //	int perl_argc = 3;
-	char *perl_argv[] = {"", "Backend.pl"};
+	char *perl_argv[] = {"", "-I" DATADIR "/script", "Backend.pl"};
 	int perl_argc = 2;
 	my_perl = perl_alloc();
 	if ( my_perl == NULL )