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

libgloss/riscv/sys_read.c

@@ -0,0 +1,9 @@
+#include <machine/syscall.h>
+#include <sys/types.h>
+#include "internal_syscall.h"
+
+/* Read from a file.  */
+ssize_t _read(int file, void *ptr, size_t len)
+{
+  return syscall_errno (SYS_read, file, ptr, len, 0, 0, 0);
+}