[librsvg] length.rs: Turn doc comments into normal comments to avoid warnings

[Federico Mena Quintero <federico src gnome org>]

commit 1de30a78dde82e89689fb1984425f6b7b8a83154
Author: Federico Mena Quintero <federico gnome org>
Date:   Thu Aug 1 10:51:28 2019 -0500

    length.rs: Turn doc comments into normal comments to avoid warnings
    
    This relates to rustdoc not generating docs for macro expansions;
    we'll fix this later.

 rsvg_internals/src/length.rs | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)
---
diff --git a/rsvg_internals/src/length.rs b/rsvg_internals/src/length.rs
index 7d6d95eb..61dce675 100644
--- a/rsvg_internals/src/length.rs
+++ b/rsvg_internals/src/length.rs
@@ -156,22 +156,22 @@ macro_rules! define_length_type {
     };
 }
 
-/// Horizontal length
-///
-/// When this is specified as a percent value, it will get resolved
-/// against the current viewport's width.
+// Horizontal length
+//
+// When this is specified as a percent value, it will get resolved
+// against the current viewport's width.
 define_length_type!(LengthHorizontal, LengthDir::Horizontal);
 
-/// Vertical length
-///
-/// When this is specified as a percent value, it will get resolved
-/// against the current viewport's height.
+// Vertical length
+//
+// When this is specified as a percent value, it will get resolved
+// against the current viewport's height.
 define_length_type!(LengthVertical, LengthDir::Vertical);
 
-/// "Both" length
-///
-/// When this is specified as a percent value, it will get resolved
-/// against the current viewport's width and height.
+// "Both" length
+//
+// When this is specified as a percent value, it will get resolved
+// against the current viewport's width and height.
 define_length_type!(LengthBoth, LengthDir::Both);
 
 // Keep this in sync with rsvg.h:RsvgLength