Hi,
  As reported in PR 61367, the aarch64 back-end is too verbose when it
is dealing with the cost model.  I tend to agree, no other back-end is
this verbose.  So I decided to add an option to enable this verbose
output if requested.

I did NOT document it in invoke.texi because I don't feel like this is
an option which an user should use.  But I can add it if requested.

OK?  Bootstrapped and tested on aarch64-linux-gnu with no regressions.

Thanks,
Andrew Pinski

ChangeLog:
* config/aarch64/aarch64.opt (mverbose-cost-dump): New option.
* config/aarch64/aarch64.c (aarch64_rtx_costs): Use
flag_aarch64_verbose_cost instead of checking for details dump.
(aarch64_rtx_costs_wrapper): Likewise.