[gnome-calendar] flatpak: Use the modern buildsystem property

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit d07ef355557d905aef70f8ce3c983b2b34f3c934
Author: Mathieu Bridon <bochecha daitauha fr>
Date:   Mon Oct 2 18:21:01 2017 +0200

    flatpak: Use the modern buildsystem property
    
    https://bugzilla.gnome.org/show_bug.cgi?id=788469

 org.gnome.Calendar.json |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/org.gnome.Calendar.json b/org.gnome.Calendar.json
index 06db6fd..4e03ab8 100644
--- a/org.gnome.Calendar.json
+++ b/org.gnome.Calendar.json
@@ -45,7 +45,7 @@
         {
             "name": "libical",
             "cleanup": [ "/lib/cmake"],
-            "cmake": true,
+            "buildsystem": "cmake",
             "config-opts": [ "-DCMAKE_INSTALL_LIBDIR:PATH=/app/lib",
                              "-DBUILD_SHARED_LIBS:BOOL=ON" ],
             "sources": [
@@ -64,6 +64,7 @@
                 "/libexec",
                 "/share/dbus-1/services"
            ],
+            "buildsystem": "cmake",
             "config-opts": [
                 "-DENABLE_GTK=ON",
                 "-DENABLE_GOOGLE_AUTH=OFF",
@@ -77,7 +78,6 @@
                 "-DENABLE_GTK_DOC=OFF",
                 "-DENABLE_EXAMPLES=OFF"
             ],
-            "cmake": true,
             "sources": [
                 {
                     "type": "git",