Pass timezone through to the VM

What a way to discover that this was missing- PipeWire camera was
freezing unless something on the host was already streaming it…

gstclock.c:1086:gst_clock_get_internal_time:<pipewireclock0> internal time 1:01:04.622699903
gstclock.c:1129:gst_clock_get_time:<pipewireclock0> adjusted time 5123776:20:12.866176008

Well, that wasn't even caused by the TZ but it made me think to fix it..

NOTE for local dev, rebuild micro-activate now

micro-activate.rs

@@ -71,6 +71,7 @@ fn main() -> Result<(), std::io::Error> {
     //
     // Let's preserve the fixed passed-in files and set up the NixOS symlinks in the new mount.
     let resolv_conf = std::fs::read("/run/resolv.conf")?;
+    let localtime = std::fs::read("/run/localtime")?;
     assert_eq!(
         unsafe {
             mount(
@@ -83,6 +84,7 @@ fn main() -> Result<(), std::io::Error> {
         },
         0
     );
+    std::fs::write("/run/localtime", &localtime)?;
     std::fs::write("/run/resolv.conf", &resolv_conf)?;
     std::fs::write("/run/machine-id", &gen_machine_id())?;
     std::os::unix::fs::symlink(&closure, "/run/current-system")?;

munix

@@ -223,6 +223,7 @@ bwrap --unshare-all --share-net \
   --symlink "$MICROVM_CLOSURE" /run/current-system \
   --ro-bind /nix/store /nix/store \
   --file 13 /run/resolv.conf \
+  --file 14 /run/localtime \
   --dir "$XDG_RUNTIME_DIR" \
   --setenv PATH "/run/munix/muvm:/run/munix/passt:$MICROVM_CLOSURE/sw/bin" \
   "${BWRAP_ARGS[@]}" \
@@ -233,4 +234,5 @@ bwrap --unshare-all --share-net \
     -e MICROVM_CLOSURE="$MICROVM_CLOSURE" \
     -e MICROVM_UID="$MICROVM_UID" -e MICROVM_GID="$MICROVM_GID" \
     -i -t -- "${MICROVM_COMMAND[@]}" \
-  13< /etc/resolv.conf
+  13< /etc/resolv.conf \
+  14< /etc/localtime

nixosModules/default.nix

@@ -64,6 +64,7 @@ in
     services.resolved.enable = false;
     environment.etc."resolv.conf".source = "/run/resolv.conf";
     environment.etc."machine-id".source = "/run/machine-id";
+    environment.etc."localtime".source = "/run/localtime";
     environment.etc."systemd/system".source = lib.mkForce (
       utils.systemdUtils.lib.generateUnits {
         type = "system";