Tell bubblewrap to share the store.  Required for programs that use the
sandboxing features such as Epiphany.

See <https://bugs.gnu.org/40837>.
Author: Jack Hill <jackhill@jackhill.us>
---
diff --git a/Source/WebKit/UIProcess/Launcher/glib/BubblewrapLauncher.cpp b/Source/WebKit/UIProcess/Launcher/glib/BubblewrapLauncher.cpp
--- a/Source/WebKit/UIProcess/Launcher/glib/BubblewrapLauncher.cpp
+++ b/Source/WebKit/UIProcess/Launcher/glib/BubblewrapLauncher.cpp
@@ -737,6 +737,9 @@ GRefPtr<GSubprocess> bubblewrapSpawn(GSubprocessLauncher* launcher, const Proces
         "--ro-bind-try", "/usr/local/share", "/usr/local/share",
         "--ro-bind-try", DATADIR, DATADIR,
 
+       // Bind mount the store inside the WebKitGTK sandbox.
+       "--ro-bind", "@storedir@", "@storedir@",
+
         // We only grant access to the libdirs webkit is built with and
         // guess system libdirs. This will always have some edge cases.
         "--ro-bind-try", "/lib", "/lib",