flatpak: 1.2.4 -> 1.4.2

* Regenerated all patches for 1.4.2 and resolved
  any conflicts.

* fix-test-paths.patch doesn't copy the whole locale archive
  because we have C.UTF8 now.

* nixos/flatpak creates a Flatpak system helper user
  Change introduced in 1.3.2.

Changes:
See https://github.com/flatpak/flatpak/releases/tag/1.3.1 through
1.4.2.

pkgs/development/libraries/flatpak/bubblewrap-paths.patch

@@ -1,8 +1,8 @@
 diff --git a/icon-validator/validate-icon.c b/icon-validator/validate-icon.c
-index 6e23d9f2..8c621ec4 100644
+index 9e885070..d02eeb8c 100644
 --- a/icon-validator/validate-icon.c
 +++ b/icon-validator/validate-icon.c
-@@ -149,8 +149,8 @@ rerun_in_sandbox (const char *arg_width,
+@@ -156,8 +156,8 @@ rerun_in_sandbox (const char *arg_width,
              "--unshare-ipc",
              "--unshare-net",
              "--unshare-pid",