...but for safety, leave the configure.ac check in for some longer.

o3tl::array_view::max_size (include/o3tl/array_view.hxx) and
o3tl::basic_string_view::max_size (include/o3tl/string_view.hxx) started to
produce loplugin:staticmethods warnings, which I silenced by /not/ making the
functions static.  Those classes are meant to be temporary drop-in replacements
for standard classes (std::span slated for C++20, prev. std::array_view; and
std::basic_string_view, resp.), so should have the same behavior as their
standard counterparts (and making the functions static would likely cause
loplugin:staticaccess warnings at call sites).

Change-Id: If21674dbf02886f453ca447544e37b184df5a25e
Reviewed-on: https://gerrit.libreoffice.org/64768
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>