Directly print OpenScop statement bodies when possible
The OpenScop format may embed a textual representation of the
statement bodies. If this is the case, print those bodies
during pretty printing instead of preprocessor directives.
This patch adds the OpenScop input to the CloogOption structure.
This was planned since OpenScop extensions will provide more and more
ways to tune the code generation experience. Hence, this single field
will embed all of them, ensuring no code changes on CloogOptions
in upcoming OpenScop-related patches.