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

fusl/src/stat/fchmod.c

Index: fusl/src/stat/fchmod.c
diff --git a/fusl/src/stat/fchmod.c b/fusl/src/stat/fchmod.c
new file mode 100644
index 0000000000000000000000000000000000000000..93e1b64c57f9046b5446292360f1564611307db7
--- /dev/null
+++ b/fusl/src/stat/fchmod.c
@@ -0,0 +1,21 @@
+#include <sys/stat.h>
+#include <errno.h>
+#include <fcntl.h>
+#include "syscall.h"
+
+void __procfdname(char *, unsigned);
+
+int fchmod(int fd, mode_t mode)
+{
+	int ret = __syscall(SYS_fchmod, fd, mode);
+	if (ret != -EBADF || __syscall(SYS_fcntl, fd, F_GETFD) < 0)
+		return __syscall_ret(ret);
+
+	char buf[15+3*sizeof(int)];
+	__procfdname(buf, fd);
+#ifdef SYS_chmod
+	return syscall(SYS_chmod, buf, mode);
+#else
+	return syscall(SYS_fchmodat, AT_FDCWD, buf, mode);
+#endif
+}