[librsvg] opacity_to_u8(): Make public

[Federico Mena Quintero <federico src gnome org>]

commit b5c440e429db4aad7d9fa4f361fcc6c37abea4df
Author: Federico Mena Quintero <federico gnome org>
Date:   Wed May 31 16:21:27 2017 -0500

    opacity_to_u8(): Make public

 rust/src/opacity.rs |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/rust/src/opacity.rs b/rust/src/opacity.rs
index c9e6d35..9672bab 100644
--- a/rust/src/opacity.rs
+++ b/rust/src/opacity.rs
@@ -59,7 +59,7 @@ impl From<Result<Opacity, AttributeError>> for OpacitySpec {
     }
 }
 
-fn opacity_to_u8 (val: f64) -> u8 {
+pub fn opacity_to_u8 (val: f64) -> u8 {
     (val * 255.0 + 0.5).floor () as u8
 }