This is a follow up patch from #90611 which folds logl calls in the same
manner as log.f128 calls. logl suffers from the same problem as logf128
of having slow calls to fp128 log functions which can be constant
folded. However, logl is emitted with -fmath-errno and log.f128 is
emitted by -fno-math-errno by certain intrinsics.
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