* the FindSDL2 module forwards to CONFIG mode first
* if that fails (eg. no -version.cmake or config not even present) it
uses pkg-config
* exports SDL2::SDL2 and SDL2::SDL2main as targets
* fix missing IMPORTED_LOCATION for other build types in Vorbisfile
It seems that FIND_PACKAGE_HANDLE_STANDARD_ARGS is doing a case-sensitive
search for whether the find_package flags included REQUIRED.
(cherry-picked from commit f259976659)
