pub const MYSQL_COMPILE_OS: &str;Expand description
What @@version_compile_os answers.
v7.39 — SPG did not have this variable at all, and answered YES to
have_ssl, which MySQL REMOVED in 8.0.26 and 9.7.2 does not answer
on either surface (measured). The two go together: one invented a
variable the engine does not have, the other was missing one it does.
The value is derived from the build target rather than hard-coded,
because a constant "Linux" would be a lie on the macOS testbed this
is developed on — and a variable whose whole purpose is to say where
the server was built is a poor place to start lying. no_std here,
so this is cfg! rather than std::env::consts::OS.