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

fusl/include/utmp.h

+#ifndef _UTMP_H
+#define _UTMP_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <utmpx.h>
+
+#define ACCOUNTING 9
+#define UT_NAMESIZE 32
+#define UT_HOSTSIZE 256
+#define UT_LINESIZE 32
+
+struct lastlog {
+        time_t ll_time;
+        char ll_line[UT_LINESIZE];
+        char ll_host[UT_HOSTSIZE];
+};
+
+#define ut_time ut_tv.tv_sec
+#define ut_name ut_user
+#define ut_addr ut_addr_v6[0]
+#define utmp utmpx
+#define utmpname(x) (-1)
+#define e_exit __e_exit
+#define e_termination __e_termination
+
+void         endutent(void);
+struct utmp *getutent(void);
+struct utmp *getutid(const struct utmp *);
+struct utmp *getutline(const struct utmp *);
+struct utmp *pututline(const struct utmp *);
+void         setutent(void);
+
+void updwtmp(const char *, const struct utmp *);
+
+int login_tty(int);
+
+#define _PATH_UTMP "/dev/null/utmp"
+#define _PATH_WTMP "/dev/null/wtmp"
+
+#define UTMP_FILE _PATH_UTMP
+#define WTMP_FILE _PATH_WTMP
+#define UTMP_FILENAME _PATH_UTMP
+#define WTMP_FILENAME _PATH_WTMP
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif