Add some keep_alive()s for use with slow targets.

src/target/riscv/batch.c

@@ -44,6 +44,8 @@ bool riscv_batch_full(struct riscv_batch *batch)
 
 void riscv_batch_run(struct riscv_batch *batch)
 {
+	keep_alive();
+
 	LOG_DEBUG("running a batch of %ld scans", (long)batch->used_scans);
 	riscv_batch_add_nop(batch);
 

src/target/riscv/program.c

@@ -41,6 +41,8 @@ int riscv_program_init(struct riscv_program *p, struct target *target)
 
 int riscv_program_exec(struct riscv_program *p, struct target *t)
 {
+	keep_alive();
+
 	if (riscv_debug_buffer_leave(t, p) != ERROR_OK) {
 		LOG_ERROR("unable to write program buffer exit code");
 		return ERROR_FAIL;