build: add libdazzle dependency

Now that libdazzle can compile on gtk+-3 3.22 again, we can use it and
still keep things working on Debian stable, RHEL, etc.

build-aux/flatpak/org.gnome.Sysprof3.json

@@ -81,6 +81,21 @@
                 }
             ]
         },
+        {
+            "name" : "libdazzle",
+            "config-opts" : [
+                "--libdir=/app/lib",
+                "--buildtype=debugoptimized"
+            ],
+            "buildsystem" : "meson",
+            "builddir" : true,
+            "sources" : [
+                {
+                    "type" : "git",
+                    "url" : "https://gitlab.gnome.org/GNOME/libdazzle.git"
+                }
+            ]
+        },
         {
             "name" : "sysprof",
             "config-opts" : [
@@ -94,7 +109,7 @@
             "sources" : [
                 {
                     "type" : "git",
-                    "url" : "https://git.gnome.org/browse/sysprof"
+                    "url" : "https://gitlab.gnome.org/GNOME/sysprof.git"
                 }
             ]
         }