[shotwell] ColorTransformation: Round up slice length

[Jens Georg <jensgeorg src gnome org>]

commit e9f8c2498d7364981f1fdf3ab30072e51f4e2720
Author: Jens Georg <mail jensge org>
Date:   Tue Nov 7 09:17:37 2017 +0100

    ColorTransformation: Round up slice length
    
    Otherwise we miss a couple of lines at the end.

 src/ColorTransformation.vala |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/src/ColorTransformation.vala b/src/ColorTransformation.vala
index 8d9ea8f..0ba8b1d 100644
--- a/src/ColorTransformation.vala
+++ b/src/ColorTransformation.vala
@@ -775,7 +775,7 @@ public class PixelTransformer {
 
         uint slice_length = dest_height;
         if (jobs > 0) {
-            slice_length = dest_height / jobs;
+            slice_length = (dest_height + (jobs - 1)) / jobs;
         }
 
         var threads = new GLib.Thread<void *>[jobs];
@@ -842,7 +842,7 @@ public class PixelTransformer {
 
         uint slice_length = height;
         if (jobs > 0) {
-            slice_length = height / jobs;
+            slice_length = (height + (jobs - 1)) / jobs;
         }
 
         var threads = new GLib.Thread<void*>[jobs];