FPHSA: Improve support for multiple alternatives
Cc: @DerDakon
Currently FPHSA receives a REQUIRED_VARS
list, tests that they are all set, and then constructs an error message reporting those missing. This does not support the case of multiple alternatives. If a find module can work with either FOO_LIBRARY_RELEASE
or FOO_LIBRARY_DEBUG
then using select_library_configurations
first to pass FOO_LIBRARY
as the required variable will not tell the users what variables they actually need to set.