bug#40741: Cannot build 27.0.91 on macOS 10.6.4

[Tak Kunihiro]

>>> The second pretest for what will be the 27.1 release of Emacs (the
>>> extensible text editor) is available at
>>>
>>>   https://alpha.gnu.org/gnu/emacs/pretest/emacs-27.0.91.tar.xz
>> 
>> I cannot build emacs 27.0.91 on macOS 10.6.4 with Xcode 11.3.1.
>> I can build emacs 26.3 on the same environment.
> 
> I believe this is a duplicate of bug#36172, as linked on that page.
> 
> Are you using any flags with configure?

I saw suggestion on bug#36172 to call following command.  That did not
change situation.

  sudo xcode-select -s /Applications/Xcode.app

I call both `./configure' and `make' without any options.