Add a "fork" of musl as //fusl.

fusl/include/utmpx.h

+#ifndef _UTMPX_H
+#define _UTMPX_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <features.h>
+
+#define __NEED_pid_t
+#define __NEED_time_t
+#define __NEED_suseconds_t
+#define __NEED_struct_timeval
+
+#include <bits/alltypes.h>
+
+struct utmpx
+{
+        short ut_type;
+        pid_t ut_pid;
+        char ut_line[32];
+        char ut_id[4];
+        char ut_user[32];
+        char ut_host[256];
+        struct {
+                short __e_termination;
+                short __e_exit;
+        } ut_exit;
+        long ut_session;
+        struct timeval ut_tv;
+        unsigned ut_addr_v6[4];
+        char __unused[20];
+};
+
+void          endutxent(void);
+struct utmpx *getutxent(void);
+struct utmpx *getutxid(const struct utmpx *);
+struct utmpx *getutxline(const struct utmpx *);
+struct utmpx *pututxline(const struct utmpx *);
+void          setutxent(void);
+
+#if defined(_BSD_SOURCE) | defined(_GNU_SOURCE)
+#define e_exit __e_exit
+#define e_termination __e_termination
+void updwtmpx(const char *, const struct utmpx *);
+#endif
+
+#define EMPTY           0
+#define RUN_LVL         1
+#define BOOT_TIME       2
+#define NEW_TIME        3
+#define OLD_TIME        4
+#define INIT_PROCESS    5
+#define LOGIN_PROCESS   6
+#define USER_PROCESS    7
+#define DEAD_PROCESS    8
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif