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/unset-env-vars.patch

@@ -1,6 +1,8 @@
+diff --git a/common/flatpak-run.c b/common/flatpak-run.c
+index 8d52d3a5..81700183 100644
 --- a/common/flatpak-run.c
 +++ b/common/flatpak-run.c
-@@ -1192,6 +1192,7 @@ static const ExportData default_exports[] = {
+@@ -1232,6 +1232,7 @@ static const ExportData default_exports[] = {
    {"PERLLIB", NULL},
    {"PERL5LIB", NULL},
    {"XCURSOR_PATH", NULL},