Fix reading of non-general registers for hwthread

Previously the code made the assumption (which is valid for conventional
RTOSs) that special registers (e.g. CSRs) are the same across threads.

26/45 tests pass.

Change-Id: Ibb3398790d7354a995d506772375d869f608f1f0

src/server/gdb_server.c

@@ -96,7 +96,7 @@ struct gdb_connection {
 	char *thread_list;
 };
 
-#if 0
+#if 1
 #define _DEBUG_GDB_IO_
 #endif