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

fusl/src/linux/process_vm.c

+#define _GNU_SOURCE
+#include <sys/uio.h>
+#include "syscall.h"
+
+ssize_t process_vm_writev(pid_t pid, const struct iovec *lvec, unsigned long liovcnt, const struct iovec *rvec, unsigned long riovcnt, unsigned long flags)
+{
+        return syscall(SYS_process_vm_writev, pid, lvec, liovcnt, rvec, riovcnt, flags);
+}
+
+ssize_t process_vm_readv(pid_t pid, const struct iovec *lvec, unsigned long liovcnt, const struct iovec *rvec, unsigned long riovcnt, unsigned long flags)
+{
+        return syscall(SYS_process_vm_readv, pid, lvec, liovcnt, rvec, riovcnt, flags);
+}