[librsvg] marker.rs: Remove unused mut

[Federico Mena Quintero <federico src gnome org>]

commit b6fda463b2a95611d069bfa649cf9afae7c8e1db
Author: Federico Mena Quintero <federico gnome org>
Date:   Tue Feb 7 16:21:22 2017 -0600

    marker.rs: Remove unused mut

 rust/src/marker.rs |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/rust/src/marker.rs b/rust/src/marker.rs
index a4808a8..95f2186 100644
--- a/rust/src/marker.rs
+++ b/rust/src/marker.rs
@@ -313,7 +313,7 @@ fn normalize_angle (mut angle: f64) -> f64 {
 }
 
 fn angle_from_vector (vx: f64, vy: f64) -> f64 {
-    let mut angle = vy.atan2 (vx);
+    let angle = vy.atan2 (vx);
 
     if angle.is_nan () {
         0.0