[shotwell] flatpak: Minor build changes

[Jens Georg <jensgeorg src gnome org>]

commit 5016b6e9c431a59d042e6c6056da798705df65fa
Author: Jens Georg <mail jensge org>
Date:   Thu Jan 3 14:56:36 2019 +0100

    flatpak: Minor build changes
    
     - Use Release build type
     - Explicitly enable pc file generation
     - Use ninja to build

 flatpak/org.gnome.Shotwell.json | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
---
diff --git a/flatpak/org.gnome.Shotwell.json b/flatpak/org.gnome.Shotwell.json
index a219a664..f01c87dd 100644
--- a/flatpak/org.gnome.Shotwell.json
+++ b/flatpak/org.gnome.Shotwell.json
@@ -183,13 +183,15 @@
         },
         {
             "name" : "opencv",
-            "buildsystem" : "cmake",
+            "buildsystem" : "cmake-ninja",
             "builddir" : true,
             "cleanup" : [
                 "/share/OpenCV/*.cmake",
                 "/share/OpenCV/*.supp"
             ],
             "config-opts" : [
+                "-DCMAKE_BUILD_TYPE=Release",
+                "-DOPENCV_GENERATE_PKGCONFIG=ON",
                 "-DBUILD_TESTS=OFF",
                 "-DBUILD_EXAMPLES=OFF",
                 "-DBUILD_PERF_TESTS=OFF",