doc: Database#busy_timeout= renders without its description (shadowed by alias_method in database.rb) #772

Summary

The generated docs show Database#busy_timeout= with no description. Its rdoc comment in ext/sqlite3/database.c ("Indicates that if a request for a resource terminates because that resource is busy, …") is never rendered, on main too, so anything added to that comment is invisible in the published docs. #771 adds text there about holding the GVL and deferring interrupts, which is how this came up.

Cause

lib/sqlite3/database.rb:387:

alias_method :busy_timeout, :busy_timeout=

When RDoc (8.1.0 here) parses this, it creates an undocumented busy_timeout= entry for SQLite3::Database, and that entry takes the place of the C method's documentation.

Checked by running rdoc on subsets of the files:

Suggested fix

Define the alias in C, next to the method, and drop the Ruby alias_method:

    rb_define_method(cSqlite3Database, "busy_timeout=", set_busy_timeout, 1);
    rb_define_alias(cSqlite3Database, "busy_timeout", "busy_timeout=");

With that change, the busy_timeout= description renders, and busy_timeout still appears as "Alias for: busy_timeout=". Runtime behaviour is unchanged, since both define the same alias on SQLite3::Database.

I haven't included this in #771 to keep that PR focused. Happy to open a separate PR if you'd like.