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

fusl/include/pwd.h

+#ifndef _PWD_H
+#define _PWD_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <features.h>
+
+#define __NEED_size_t
+#define __NEED_uid_t
+#define __NEED_gid_t
+
+#ifdef _GNU_SOURCE
+#define __NEED_FILE
+#endif
+
+#include <bits/alltypes.h>
+
+struct passwd
+{
+        char *pw_name;
+        char *pw_passwd;
+        uid_t pw_uid;
+        gid_t pw_gid;
+        char *pw_gecos;
+        char *pw_dir;
+        char *pw_shell;
+};
+
+void setpwent (void);
+void endpwent (void);
+struct passwd *getpwent (void);
+
+struct passwd *getpwuid (uid_t);
+struct passwd *getpwnam (const char *);
+int getpwuid_r (uid_t, struct passwd *, char *, size_t, struct passwd **);
+int getpwnam_r (const char *, struct passwd *, char *, size_t, struct passwd **);
+
+#ifdef _GNU_SOURCE
+struct passwd *fgetpwent(FILE *);
+int putpwent(const struct passwd *, FILE *);
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif