Write a pid when we daemonize

patch by Mike Frysinger

--- a/bmon.c
+++ b/mbmon.c
@@ -229,4 +229,5 @@
 static void daemonize()
 {
+	pid_t pid;
 	int fd;
 	struct sigaction sa_ign, sa_save;
@@ -247,5 +248,5 @@
 	sigaction(SIGHUP, &sa_ign, &sa_save);
 
-	switch (fork()) {
+	switch ((pid=fork())) {
 	case 0:
 		break;
@@ -259,4 +260,11 @@
 
 	default:
+		{
+		FILE *f = fopen("/var/run/mbmon.pid", "w");
+		if (f != NULL) {
+			fprintf(f, "%i", pid);
+			fclose(f);
+		}
+		}
 		exit(0);
 		/* NOTREACHED */