Increase BB to explore for reachability analysis

We pass mcpu=cortex-a55 for our build, which increases BB to the point
where the LLVM default of 32 is not enough.

I ran a fullmte build and did not see any slowdown.

Bug: 229654778
Change-Id: Ifbd1e5427101b2f2f39c067ba3ea4d5cb4a3ba0d