Most recent version of XQuartz, same as before. Unfortunately,
newer version of macOS => newer version of Xcode and its command
line tools => newer version of clang => emulating newer version of
gcc which defaults to a more recent version of StdC, I suppose, or
perhaps our hints are specifying that. Whichever, it has resulted
in a bunch of complaints about XtOffset() used in win/X11/winX.c:
|warning: performing pointer subtraction with a null pointer has\
undefined behavior [-Wnull-pointer-subtraction]
Adding -wno-null-pointer-subtraction to X11FLAGS silences them,
but that would require figuring out which versions of gcc and
clang added -Wnull-pointer-subtraction and its negation. Revising
XtOffset() to include the ptrdiff_t casts eliminates the warnings,
avoiding the need for version conditionals to deal with X11FLAGS.
82c6804516