Use proper import path go.etcd.io/bbolt

Signed-off-by: Robert-André Mauchin <zebob.m@gmail.com>

vendor/go.etcd.io/bbolt/boltsync_unix.go

@@ -0,0 +1,8 @@
+// +build !windows,!plan9,!linux,!openbsd
+
+package bbolt
+
+// fdatasync flushes written data to a file descriptor.
+func fdatasync(db *DB) error {
+	return db.file.Sync()
+}