rcu: Make tiny RCU support leak callbacks for debug-object errors

Currently, only Tree RCU leaks callbacks setting when it detects a
duplicate call_rcu().  This commit causes Tiny RCU to also leak
callbacks in this situation.

Because this is Tiny RCU, kernel size is important:

1. CONFIG_TINY_RCU=y and CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
   (Production kernel)

    Original:
    text      data      bss       dec       hex     filename
    26290663  20159823  15212544  61663030  3ace736 vmlinux

    With this commit:
    text      data      bss       dec       hex     filename
    26290663  20159823  15212544  61663030  3ace736 vmlinux

2. CONFIG_TINY_RCU=y and CONFIG_DEBUG_OBJECTS_RCU_HEAD=y
   (Debugging kernel)

    Original:
    text      data      bss       dec       hex     filename
    26291319  20160143  15212544  61664006  3aceb06 vmlinux

    With this commit:
    text      data      bss       dec       hex     filename
    26291319  20160431  15212544  61664294  3acec26 vmlinux

These results show that the kernel size is unchanged for production
kernels, as desired.

Signed-off-by: Zqiang <qiang1.zhang@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>