Initialize all registers in examine

I'm not sure why this is necessary, but for some reason GDB is asking
for registers before OpenOCD thinks there's been a halt.  This is really
just a workaround, but I need to refactor the v0.11 stuff anyway so I
don't want to figure it out.

src/target/riscv/riscv-011.c

@@ -1910,6 +1910,9 @@ static int examine(struct target *target)
 	}
 
 	target_set_examined(target);
+	riscv_set_current_hartid(target, 0);
+	for (size_t i = 0; i < 32; ++i)
+		reg_cache_set(target, i, -1);
 	LOG_INFO("Examined RISCV core; XLEN=%d, misa=0x%" PRIx64, riscv_xlen(target), info->misa);
 
 	return ERROR_OK;