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

fusl/src/time/__map_file.c

+#include <sys/mman.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include "syscall.h"
+
+void *__mmap(void *, size_t, int, int, int, off_t);
+
+const char unsigned *__map_file(const char *pathname, size_t *size)
+{
+        struct stat st;
+        const unsigned char *map = MAP_FAILED;
+        int fd = __sys_open(pathname, O_RDONLY|O_CLOEXEC|O_NONBLOCK);
+        if (fd < 0) return 0;
+        if (!__syscall(SYS_fstat, fd, &st)) {
+                map = __mmap(0, st.st_size, PROT_READ, MAP_SHARED, fd, 0);
+                *size = st.st_size;
+        }
+        __syscall(SYS_close, fd);
+        return map == MAP_FAILED ? 0 : map;
+}