Use RPM's build conditionals to control which policy types to build
    
    Instead of plain macros, use `%bcond ...` and `%{with ...}`, which will
    allow controlling which policy types to build using the --with/--without
    command-line arguments when calling `rpmbuild` or `mock`.
    
    See also:
    https://rpm-software-management.github.io/rpm/manual/conditionalbuilds.html
    
    Note that the BUILD_DOC macro is removed without replacement as it's
    unused. (The builds of the -doc and -devel subpackages overlap too much
    for the macro to be useful, anyway.)
    
    Signed-off-by: Ondrej Mosnáček <omosnacek@gmail.com>