Switched to Perl local::lib for local compilation.

Taken from upstream Slic3r, thanks @alexrj.

t/angles.t

@@ -7,6 +7,7 @@ plan tests => 34;
 BEGIN {
     use FindBin;
     use lib "$FindBin::Bin/../lib";
+    use local::lib "$FindBin::Bin/../local-lib";
 }
 
 use Slic3r;