[PowerPC] Mark jumps as expensive (using using CR bits)
On PowerPC, which has a full set of logical operations on (its multiple sets
of) condition-register bits, it is not profitable to break of complex
conditions feeding a jump into multiple jumps. We can turn off this feature of
CGP/SDAGBuilder by marking jumps as "expensive".
P7 test-suite speedups (no regressions):
-0.626647% +/- 0.323583%
-18.2821% +/- 8.06481%