RISC-V: Moved syscalls to separate files to fix aliasing problems.

libgloss/riscv/sys_fork.c

@@ -0,0 +1,10 @@
+#include <machine/syscall.h>
+#include "internal_syscall.h"
+
+/* Create a new process. Minimal implementation for a system without
+   processes from newlib documentation.  */
+int _fork()
+{
+  errno = EAGAIN;
+  return -1;
+}