Tell bubblewrap to share the store, and _not_ to share traditional FHS
directories that are not used in Guix.  Required for programs that use the
sandboxing features such as Epiphany.

See <https://bugs.gnu.org/40837> and <https://bugs.gnu.org/47628>.
Authors: Jack Hill <jackhill@jackhill.us> and Mark H Weaver <mhw@netris.org>.

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
@@ -749,26 +749,18 @@
         "--ro-bind", "/sys/dev", "/sys/dev",
         "--ro-bind", "/sys/devices", "/sys/devices",
 
-        "--ro-bind-try", "/usr/share", "/usr/share",
-        "--ro-bind-try", "/usr/local/share", "/usr/local/share",
         "--ro-bind-try", DATADIR, DATADIR,
 
-        // 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",
-        "--ro-bind-try", "/usr/lib", "/usr/lib",
-        "--ro-bind-try", "/usr/local/lib", "/usr/local/lib",
-        "--ro-bind-try", LIBDIR, LIBDIR,
-        "--ro-bind-try", "/lib64", "/lib64",
-        "--ro-bind-try", "/usr/lib64", "/usr/lib64",
-        "--ro-bind-try", "/usr/local/lib64", "/usr/local/lib64",
+        // Bind mount the store inside the WebKitGTK sandbox.
+        "--ro-bind", "@storedir@", "@storedir@",
 
+        // We only grant access to the libdirs webkit is built with.
+        "--ro-bind-try", LIBDIR, LIBDIR,
         "--ro-bind-try", PKGLIBEXECDIR, PKGLIBEXECDIR,
     };
 
     if (launchOptions.processType == ProcessLauncher::ProcessType::DBusProxy) {
         sandboxArgs.appendVector(Vector<CString>({
-            "--ro-bind", "/usr/bin", "/usr/bin",
             // This is a lot of access, but xdg-dbus-proxy is trusted so that's OK. It's sandboxed
             // only because we have to mount .flatpak-info in its mount namespace. The user rundir
             // is where we mount our proxy socket.