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

libgloss/riscv/sys_chown.c

@@ -0,0 +1,8 @@
+#include <machine/syscall.h>
+#include <sys/types.h>
+
+/* Stub.  */
+int _chown(const char *path, uid_t owner, gid_t group)
+{
+  return -1;
+}