accel/tcg: Set cflags_next_tb in cpu_common_initfn

While we initialize this value in cpu_common_reset, that
isn't called during startup, so set it as well in init.
This fixes -singlestep versus the very first TB.

Fixes: 04f5b647ed07 ("accel/tcg: Handle -singlestep in curr_cflags")
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

hw/core/cpu-common.c

@@ -235,6 +235,7 @@ static void cpu_common_initfn(Object *obj)
     /* the default value is changed by qemu_init_vcpu() for softmmu */
     cpu->nr_cores = 1;
     cpu->nr_threads = 1;
+    cpu->cflags_next_tb = -1;
 
     qemu_mutex_init(&cpu->work_mutex);
     QSIMPLEQ_INIT(&cpu->work_list);