This depth limits a linear search (rather than the usual potentially
exponential one) and is not particularly important for compile-time in
practice.
The change in #137297 is going to increase the length of GEP chains, so
I'd like to increase this limit a bit to reduce the chance of
regressions (https://github.com/dtcxzyw/llvm-opt-benchmark/pull/2419
showed a 13% increase in SearchLimitReached). There is no particular
significance to the new value of 10.
Compile-time is neutral.
6157028fea