[$] Data-type profiling for perf

Tooling for profiling the effects of memory usage and layout has always
lagged behind that for profiling processor activity, so Namhyung Kim's patch set for data-type profiling
in perf is a welcome addition. It provides aggregated breakdowns of
memory accesses by data type that can inform structure layout and access
pattern changes. Existing tools have either, like heaptrack, focused on
profiling allocations, or, like perf mem, on accounting memory
accesses only at the address level. This new work builds on the latter,
using DWARF debugging information to correlate memory operations with their
source-level types.