[librsvg] parse_or_value(): implement in terms of Option::unwrap_or()

[Federico Mena Quintero <federico src gnome org>]

commit 5409facf6dfa3deac900a53b9345b4bbd9657d30
Author: Federico Mena Quintero <federico gnome org>
Date:   Tue Sep 5 10:10:41 2017 -0500

    parse_or_value(): implement in terms of Option::unwrap_or()

 rust/src/property_bag.rs |    8 +-------
 1 files changed, 1 insertions(+), 7 deletions(-)
---
diff --git a/rust/src/property_bag.rs b/rust/src/property_bag.rs
index 0d32b3b..bdf9559 100644
--- a/rust/src/property_bag.rs
+++ b/rust/src/property_bag.rs
@@ -73,11 +73,5 @@ pub fn parse_or_value<T> (pbag: *const RsvgPropertyBag,
                           validate: Option<fn(T) -> Result<T, AttributeError>>) -> Result <T, NodeError>
     where T: Parse<Err = AttributeError> + Copy
 {
-    let r = parse_or_none (pbag, key, data, validate);
-
-    match r {
-        Ok (Some (v)) => Ok (v),
-        Ok (None)     => Ok (value),
-        Err (e)       => Err (e)
-    }
+    Ok (parse_or_none (pbag, key, data, validate)?.unwrap_or (value))
 }