Make sure that all parameter dimensions are set in schedule

Summary:
In case the option -polly-ignore-parameter-bounds is set, not all parameters
will be added to context and domains. This is useful to keep the size of the
sets and maps we work with small. Unfortunately, for AST generation it is
necessary to ensure all parameters are part of the schedule tree. Hence,
we modify the GPGPU code generation to make sure this is the case.

To obtain the necessary information we expose a new function
Scop::getFullParamSpace(). We also make a couple of functions const to be
able to make SCoP::getFullParamSpace() const.

Reviewers: Meinersbur, bollu, gareevroman, efriedma, huihuiz, sebpop, simbuerg

Subscribers: nemanjai, kbarton, pollydev, llvm-commits

Tags: #polly

Differential Revision: https://reviews.llvm.org/D36243

llvm-svn: 309939