The algorithm added by PR #87375 can be potentially quadratic in the
number of anchors. This is almost never a problem because normally
functions have a reasonable number of function calls.
However, in some rare cases of auto-generated code we observed very
large functions that trigger quadratic behaviour here (resulting in
>130GB of peak heap memory usage for clang). Let's add a knob for
controlling the max number of callsites in a function above which stale
profile matching won't be performed.
21ba91c439