patch 9.0.1910: Mac OS X: missing sound support on older versions

patch 9.0.1910: Mac OS X: missing sound support on older versions

Problem:  Mac OS X: missing sound support on older versions
Solution: Check Macro MAC_OS_X_VERSION_MIN_REQUIRED

Extend guard for sound support on OS X

Fixes build on legacy versions where required coreaudio functionality
may not be available. NSSoundDelegate apparently was introduced in Snow
Leopard yet the build breaks on it. Guarding off enabling sound support
to El Capitan as that's the next version I had access to for testing (it
may work on earlier versions)
https://developer.apple.com/documentation/appkit/nssounddelegate Vim
builds on OS X Tiger 10.4 and newer with this change.

closes: #13115

Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: Sevan Janiyan <venture37@geeklan.co.uk>