We were sizing the table appropriately for the number of LibcallImpls,
but many of those have identical names which were pushing up the
collision count unnecessarily. This ends up decreasing the table size
slightly, and makes it a bit faster.
BM_LookupRuntimeLibcallByNameRandomCalls improves by ~25% and
BM_LookupRuntimeLibcallByNameSampleData by ~5%.
As a secondary change, align the table size up to the next
power of 2. This makes the table larger than before, but improves
the sample data benchmark by an additional 5%.
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