datastore: gc: avoid unsafe call into libc, use epoch_i64 helper

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

src/backup/datastore.rs

@@ -483,7 +483,7 @@ impl DataStore {
             // writer" information and thus no safe atime cutoff
             let _exclusive_lock =  self.chunk_store.try_exclusive_lock()?;
 
-            let phase1_start_time = unsafe { libc::time(std::ptr::null_mut()) };
+            let phase1_start_time = proxmox::tools::time::epoch_i64();
             let oldest_writer = self.chunk_store.oldest_writer().unwrap_or(phase1_start_time);
 
             let mut gc_status = GarbageCollectionStatus::default();