Replace 'class' with 'struct', since they are already defined as 'struct'
in PackageInfoAttributeValue.h
Pointed by clang [-Wmismatched-tags]
Change-Id: I094d32c3444fe4299a3afe0872ade296f92debf9
Reviewed-on: https://review.haiku-os.org/471
Reviewed-by: waddlesplash <waddlesplash@gmail.com>
92b072972b