It seems like on Unix apr_dso_load() requires a suffix for the pathname
I don't see any code in apr_dso_load() that requires that. Perhaps your OS has a requirement?
but on Windows it will provide one (.dll).
can't see such code... maybe Win32 itself adds .dll under some circumstances
WRT writing portable code...it looks like Apache itself just uses .so on all platforms
the Apache build makes some effort to name them mod_foo.so
>...or is there some other
mechanism? For example, a place where the appropriate platform-specific suffix might be acquired?