[gnome-builder] flatpak: use proper ccache dir

[Christian Hergert <chergert src gnome org>]

commit 2c1aa2cff8de2d89650f1ef35a8b17e404bffb21
Author: Christian Hergert <chergert redhat com>
Date:   Thu Mar 16 13:11:02 2017 -0700

    flatpak: use proper ccache dir
    
    Previous commit was the wrong one. This actually uses the ccache dir in
    the flatpak-builder directory.

 plugins/flatpak/gbp-flatpak-runtime.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)
---
diff --git a/plugins/flatpak/gbp-flatpak-runtime.c b/plugins/flatpak/gbp-flatpak-runtime.c
index d0a503c..383886c 100644
--- a/plugins/flatpak/gbp-flatpak-runtime.c
+++ b/plugins/flatpak/gbp-flatpak-runtime.c
@@ -133,6 +133,7 @@ gbp_flatpak_runtime_create_launcher (IdeRuntime  *runtime,
       g_autofree gchar *project_name = NULL;
       g_autofree gchar *project_path = NULL;
       g_autofree gchar *build_path = NULL;
+      g_autofree gchar *ccache_dir = NULL;
       g_auto(GStrv) new_environ = NULL;
       const gchar *builddir = NULL;
       GFile *project_file;
@@ -175,9 +176,13 @@ gbp_flatpak_runtime_create_launcher (IdeRuntime  *runtime,
       ide_subprocess_launcher_push_argv (ret, "--share=network");
 
       /* We might need access to ccache configs inside the build environ.
+       * Usually, this is set by flatpak-builder, but since we are running
+       * the incremental build, we need to take care of that too.
+       *
        * See https://bugzilla.gnome.org/show_bug.cgi?id=780153
        */
-      ide_subprocess_launcher_push_argv (ret, "--filesystem=~/.ccache");
+      ccache_dir = g_build_filename (project_path, ".flatpak-builder", "ccache", NULL);
+      ide_subprocess_launcher_setenv (ret, "CCACHE_DIR", ccache_dir, FALSE);
 
       if (!ide_str_empty0 (project_path))
         {