Increment the reference count of sessions inside the lock.

Otherwise another thread may cause the session to be destroyed first.

Change-Id: I2084a28ece11540e1b8f289553161d99395e2d1f
Reviewed-on: https://boringssl-review.googlesource.com/5231
Reviewed-by: Adam Langley <agl@google.com>
1 file changed