https://bugs.gentoo.org/597646
Port to musl libc.

--- skey-1.1.5-orig/skey.h
+++ skey-1.1.5/skey.h
@@ -67,6 +67,10 @@
 /* Location of random file for bogus challenges */
 #define _SKEY_RAND_FILE_PATH_	"/var/db/host.random"
 
+#ifndef __P
+#define __P(x) x
+#endif
+
 /* Prototypes */
 void f __P ((char *));
 int keycrunch __P ((char *, const char *, const char *));
--- skey-1.1.5-orig/skeyinit.c
+++ skey-1.1.5/skeyinit.c
@@ -36,6 +36,7 @@
 #include <syslog.h>
 #include <time.h>
 #include <unistd.h>
+#include <paths.h>
 #ifdef HAVE_CRYPT_H
 #include <crypt.h>
 #endif