[PATCH 4/8] perf diff: Add weighted diff computation way to compare hist entries

Adding 'wdiff' as new computation way to compare hist entries. If specified the 'Weighted diff' column is displayed with value 'd' computed as: d = B->period * WEIGHT-A - A->period * WEIGHT-B - A/B being matching hist entry from first/second file specified (or perf.data/perf.data.old)

[PATCH 4/8] perf diff: Add weighted diff computation way to compare hist entries

Adding 'wdiff' as new computation way to compare hist entries. If specified the 'Weighted diff' column is displayed with value 'd' computed as: d = B-period * WEIGHT-A - A-period * WEIGHT-B - A/B being matching hist entry from first/second file specified (or perf.data/perf.data.old)