perf: Implement lbr-as-callgraph v4

[All review feedback addressed.] This patchkit implements lbr-as-callgraphs in per freport, as an alternative way to present LBR information. Current perf report does a histogram over the branch edges, which is useful to look at basic blocks, but doesn't tell you anything about the larger

perf: Implement lbr-as-callgraph v4

[All review feedback addressed.] This patchkit implements lbr-as-callgraphs in per freport, as an alternative way to present LBR information. Current perf report does a histogram over the branch edges, which is useful to look at basic blocks, but doesn't tell you anything about the larger