Building Notmuch on macOS is known to cause problems because the Notmuch
distribution archive contains two files named "version". These names
clash with the <version> header as defined in C++20. Therefore, the
existing naming will likely become a problem on other platforms as well,
once compilers adopt the new standard.
Signed-off-by: Ralph Seichter <github@seichter.de>
Amended-by: db s/keyword/header/ in commit message.
