Revert "Use RegScavenging for large FI offset computation"

This reverts commit 49c47870efd6d124ee2ef712368220f7d09cd81a.

This change is more involved than expected,
continued on a separate branch.
DelaySlotFiller fix: check flag instead of opcode
Merge branch 'master' of ssh+git://github.com/t-crest/patmos-llvm