kvdb: exclude anything bbolt related from JS builds

Since bbolt uses syscalls for memory mapping that aren't available in
JS/WASM builds, we need to make sure we don't reference that code at
all. Otherwise we can't use parts of lnd as a library in projects that
are being compiled down to a WASM binary.

kvdb/bolt_compact.go

@@ -2,6 +2,8 @@
 // implemented in this file:
 // https://github.com/etcd-io/bbolt/blob/master/cmd/bbolt/main.go
 
+// +build !js
+
 package kvdb
 
 import (