swift234

LLVMARC: Don't bail on obj_retain/release or unknown_retain/release

We can remove objc_retain/releases just like swift ones.

Results -O where SU = minbefore/minafter (10 samples):

TEST`````````````````MIN``MAX``MEAN`SD```MED``MIN``MAX``MEAN`SD```MED````SU
ClassArrayGetter`````1931`1943`1938`4````1940`1143`1158`1150`5````1153```1.68
DeltaBlue````````````3434`3450`3439`4````3441`2906`2932`2913`7````2911```1.18
Dictionary```````````5616`5933`5755`112``5748`5291`5713`5515`140``5563```1.06
PopFrontArray````````103``109``104``1````104``96```99```96```1````96`````1.07
PopFrontArrayGeneric`102``106``103``1````103``95```98```96```1````96`````1.07
PrimeNum`````````````4098`7552`5953`1164`6319`4496`8653`6336`1210`6639```0.91
QuickSort````````````6380`6415`6396`11```6398`6071`6115`6086`13```6082```1.05
Rectangles```````````2277`2377`2322`31```2320`1636`1682`1657`12```1655```1.39
StrCat```````````````2811`2849`2825`12```2822`2487`2516`2501`12```2505```1.13
StringWalk```````````5784`5797`5790`4````5790`6124`6137`6129`4````6127```0.94

Swift SVN r22695