[$] Data-type profiling for perf

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