[ScopInfo] Bound the number of array disjuncts in run-time bounds checks

This reduces the compilation time of one reduced test case from Android from
16 seconds to 100 mseconds (we bail out), without negatively impacting any
other test case we currently have.

We still saw occasionally compilation timeouts on the AOSP buildbot. Hopefully,
those will go away with this change.

llvm-svn: 306235