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

fusl/include/setjmp.h

+#ifndef _SETJMP_H
+#define _SETJMP_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <features.h>
+
+#include <bits/setjmp.h>
+
+typedef struct __jmp_buf_tag {
+        __jmp_buf __jb;
+        unsigned long __fl;
+        unsigned long __ss[128/sizeof(long)];
+} jmp_buf[1];
+
+#if defined(_POSIX_SOURCE) || defined(_POSIX_C_SOURCE) \
+ || defined(_XOPEN_SOURCE) || defined(_GNU_SOURCE) \
+ || defined(_BSD_SOURCE)
+typedef jmp_buf sigjmp_buf;
+int sigsetjmp (sigjmp_buf, int);
+_Noreturn void siglongjmp (sigjmp_buf, int);
+#endif
+
+#if defined(_XOPEN_SOURCE) || defined(_GNU_SOURCE) \
+ || defined(_BSD_SOURCE)
+int _setjmp (jmp_buf);
+_Noreturn void _longjmp (jmp_buf, int);
+#endif
+
+int setjmp (jmp_buf);
+_Noreturn void longjmp (jmp_buf, int);
+
+#define setjmp setjmp
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif