The "main" component is not available everywhere, but passing it to the
find_package(SFML) call via the OPTIONAL_COMPONENTS still fails the call
on platforms like Linux.
This commit enables SFML to be used the same in a cross-platform fashion
without forcing consumers to put custom logic around importing SFML.
Example that works with this commit, but break before:
find_package(SFML REQUIRED graphics OPTIONAL_COMPONENTS main)
target_link_libraries(dummy PRIVATE SFML::graphics)
if(SFML_MAIN_FOUND)
target_link_libraries(dummy PRIVATE SFML::main)
endif()
9b3735c05f