File fix-implicit.patch of Package alpine

--- imap/src/mlock/mlock.c
+++ imap/src/mlock/mlock.c
@@ -28,6 +28,7 @@
 
 #include <errno.h>
 #include <fcntl.h>
+#include <unistd.h>
 #include <stdio.h>
 #include <sysexits.h>
 #include <syslog.h>