There is one unnecessary function called ReadView::complete(), which was
designed to be called either under trx mutex or not under trx mutex.
However, the work this function does in fact can be splitted and
re-assigned to other two functions, in this way, one 'if' checking can be
optimized out, which as reported helps the performance when using ARM64.

RB: 20152
Reviewed-by: Jimmy Yang <jimmy.yang@oracle.com>