[librsvg] pattern.rs: shorten the way we map option values

[Federico Mena Quintero <federico src gnome org>]

commit d6683eb7ebb6fe4f3efd7c82e706caf9970ed756
Author: Federico Mena Quintero <federico gnome org>
Date:   Fri Sep 1 11:30:38 2017 -0500

    pattern.rs: shorten the way we map option values
    
    Thanks to Sergey Bugaev for the tip.

 rust/src/pattern.rs |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/rust/src/pattern.rs b/rust/src/pattern.rs
index 53dd72f..901cb73 100644
--- a/rust/src/pattern.rs
+++ b/rust/src/pattern.rs
@@ -200,7 +200,7 @@ impl NodeTrait for NodePattern {
 
         p.units         = property_bag::parse_or_none (pbag, "patternUnits")?;
         p.content_units = property_bag::parse_or_none (pbag, "patternContentUnits")?;
-        p.vbox          = property_bag::parse_or_none (pbag, "viewBox")?.map (|v| Some(v)).or (None);
+        p.vbox          = property_bag::parse_or_none (pbag, "viewBox")?.map (Some).or (None);
 
         p.preserve_aspect_ratio = property_bag::parse_or_none (pbag, "preserveAspectRatio")?;