Code generate parameters and run-time checks after branching new code region

When creating parameters the SCEVexpander may introduce new induction variables,
that possibly create scalar dependences in the original scop, before we code
generate the scop. The resulting scalar dependences may then inhibit correct
code generation of the scop. To prevent this, we first version the code without
a run-time check and only then introduce new parameters and the run-time
condition. The if-condition that guards the original scop from being modified by
the SCEVexpander.

This change causes some test case changes as the run-time conditions are now
introduced in the split basic block rather than in the entry basic block.

This fixes http://llvm.org/PR22069

Test case reduced by: Karthik Senthil

llvm-svn: 233477