DARWIN_UNLIMITED_SELECT or _DARWIN_UNLIMITED_SELECT

[dsedivec]

Hi! I see you define DARWIN_UNLIMITED_SELECT when building Emacs. I can't find a mention of this define anywhere in header files. I can, however, find _DARWIN_UNLIMITED_SELECT, with the leading underscore. This is also mentioned, for example, in a CMake issue. Also, the Darwin man page for select(2) also has the leading underscore.

Are we sure -DDARWIN_UNLIMITED_SELECT is correct?