[librsvg] util.rs: Move clone_fallback_name() here

[Federico Mena Quintero <federico src gnome org>]

commit fbfdc927ad81705f61cd06719fc60ebf84c29399
Author: Federico Mena Quintero <federico gnome org>
Date:   Wed Feb 1 21:52:14 2017 -0600

    util.rs: Move clone_fallback_name() here
    
    We'll use it in the patterns code as well

 rust/src/gradient.rs |   10 ++--------
 rust/src/util.rs     |   12 +++++++++++-
 2 files changed, 13 insertions(+), 9 deletions(-)
---
diff --git a/rust/src/gradient.rs b/rust/src/gradient.rs
index 887f225..f3f7ce8 100644
--- a/rust/src/gradient.rs
+++ b/rust/src/gradient.rs
@@ -13,6 +13,8 @@ use drawing_ctx::RsvgNode;
 
 use bbox::*;
 
+use util::*;
+
 use self::cairo::MatrixTrait;
 
 #[derive(Copy, Clone)]
@@ -133,14 +135,6 @@ impl GradientCommon {
     }
 }
 
-fn clone_fallback_name (fallback: &Option<String>) -> Option<String> {
-    if let Some (ref fallback_name) = *fallback {
-        Some (fallback_name.clone ())
-    } else {
-        None
-    }
-}
-
 impl Clone for GradientCommon {
     fn clone (&self) -> Self {
         GradientCommon {
diff --git a/rust/src/util.rs b/rust/src/util.rs
index b3f09e7..4cd80b2 100644
--- a/rust/src/util.rs
+++ b/rust/src/util.rs
@@ -1,4 +1,14 @@
-const DBL_EPSILON: f64 = 1e-10;
+// In paint servers (patterns, gradients, etc.), we have an
+// Option<String> for fallback names.  This is a utility function to
+// clone one of those.
+pub fn clone_fallback_name (fallback: &Option<String>) -> Option<String> {
+    if let Some (ref fallback_name) = *fallback {
+        Some (fallback_name.clone ())
+    } else {
+        None
+    }
+}
+
 pub const DBL_EPSILON: f64 = 1e-10;
 
 pub fn double_equals (a: f64, b: f64) -> bool {