signal: handle shutdown properly

This addresses issues related to the mobile lnd builds, where
calling `stopDaemon` and subsequently calling LndMobile's `Start`
results in crash.

config.go

@@ -36,6 +36,7 @@ import (
 	"github.com/lightningnetwork/lnd/lnrpc/signrpc"
 	"github.com/lightningnetwork/lnd/lnwallet"
 	"github.com/lightningnetwork/lnd/routing"
+	"github.com/lightningnetwork/lnd/signal"
 	"github.com/lightningnetwork/lnd/tor"
 )
 
@@ -510,7 +511,7 @@ func DefaultConfig() Config {
 // 	2) Pre-parse the command line to check for an alternative config file
 // 	3) Load configuration file overwriting defaults with any specified options
 // 	4) Parse CLI options and overwrite/add any specified options
-func LoadConfig() (*Config, error) {
+func LoadConfig(interceptor signal.Interceptor) (*Config, error) {
 	// Pre-parse the command line options to pick up an alternative config
 	// file.
 	preCfg := DefaultConfig()
@@ -563,7 +564,7 @@ func LoadConfig() (*Config, error) {
 	}
 
 	// Make sure everything we just loaded makes sense.
-	cleanCfg, err := ValidateConfig(cfg, usageMessage)
+	cleanCfg, err := ValidateConfig(cfg, usageMessage, interceptor)
 	if err != nil {
 		return nil, err
 	}
@@ -581,7 +582,8 @@ func LoadConfig() (*Config, error) {
 // ValidateConfig check the given configuration to be sane. This makes sure no
 // illegal values or combination of values are set. All file system paths are
 // normalized. The cleaned up config is returned on success.
-func ValidateConfig(cfg Config, usageMessage string) (*Config, error) {
+func ValidateConfig(cfg Config, usageMessage string,
+	interceptor signal.Interceptor) (*Config, error) {
 	// If the provided lnd directory is not the default, we'll modify the
 	// path to all of the files and directories that will live within it.
 	lndDir := CleanAndExpandPath(cfg.LndDir)
@@ -1151,7 +1153,7 @@ func ValidateConfig(cfg Config, usageMessage string) (*Config, error) {
 	}
 
 	// Initialize logging at the default logging level.
-	SetupLoggers(cfg.LogWriter)
+	SetupLoggers(cfg.LogWriter, interceptor)
 	err = cfg.LogWriter.InitLogRotator(
 		filepath.Join(cfg.LogDir, defaultLogFilename),
 		cfg.MaxLogFileSize, cfg.MaxLogFiles,