sysroot: Add ostree_sysroot_write_deployments_with_options()

More sophisticated users of libostree like rpm-ostree need control over things
like the system repository. Previously we introduced a "no cleanup" flag to
`ostree_sysroot_simple_write_deployment()`, but that's a high level API that
does filtering on its own.

Since rpm-ostree needs more control, let's expose the bare essentials of the
"sysroot commit" operation with an extensible options structure, where one of
the options is whether or not to do post-transaction repository operations.

Closes: #745
Approved by: jlebon

src/libostree/ostree-sysroot-deploy.c

@@ -1686,8 +1686,8 @@ is_ro_mount (const char *path)
  * @cancellable: Cancellable
  * @error: Error
  *
- * Assuming @new_deployments have already been deployed in place on
- * disk, atomically update bootloader configuration.
+ * Older version of ostree_sysroot_write_deployments_with_options(). This
+ * version will perform post-deployment cleanup by default.
  */
 gboolean
 ostree_sysroot_write_deployments (OstreeSysroot     *self,
@@ -1695,16 +1695,32 @@ ostree_sysroot_write_deployments (OstreeSysroot     *self,
                                   GCancellable      *cancellable,
                                   GError           **error)
 {
-  return _ostree_sysroot_write_deployments_internal (self, new_deployments,
-                                                     TRUE, cancellable, error);
+  OstreeSysrootWriteDeploymentsOpts opts = { .do_postclean = TRUE };
+  return ostree_sysroot_write_deployments_with_options (self, new_deployments, &opts,
+                                                        cancellable, error);
 }
 
+/**
+ * ostree_sysroot_write_deployments_with_options:
+ * @self: Sysroot
+ * @new_deployments: (element-type OstreeDeployment): List of new deployments
+ * @opts: Options
+ * @cancellable: Cancellable
+ * @error: Error
+ *
+ * Assuming @new_deployments have already been deployed in place on disk via
+ * ostree_sysroot_deploy_tree(), atomically update bootloader configuration. By
+ * default, no post-transaction cleanup will be performed. You should invoke
+ * ostree_sysroot_cleanup() at some point after the transaction, or specify
+ * `do_postclean` in @opts.  Skipping the post-transaction cleanup is useful
+ * if for example you want to control pruning of the repository.
+ */
 gboolean
-_ostree_sysroot_write_deployments_internal (OstreeSysroot     *self,
-                                            GPtrArray         *new_deployments,
-                                            gboolean           do_clean,
-                                            GCancellable      *cancellable,
-                                            GError           **error)
+ostree_sysroot_write_deployments_with_options (OstreeSysroot     *self,
+                                               GPtrArray         *new_deployments,
+                                               OstreeSysrootWriteDeploymentsOpts *opts,
+                                               GCancellable      *cancellable,
+                                               GError           **error)
 {
   gboolean ret = FALSE;
   guint i;
@@ -1930,7 +1946,7 @@ _ostree_sysroot_write_deployments_internal (OstreeSysroot     *self,
 
   /* And finally, cleanup of any leftover data.
    */
-  if (do_clean)
+  if (opts->do_postclean)
     {
       if (!ostree_sysroot_cleanup (self, cancellable, error))
         {