This update for pcm fixes the following issues:

pcm was updated to 202101:

* Add Comet Lake support
* Add Tiger Lake support
* Add support for additional Icelake cpu model
* Support Linux resctrl driver for RDT Metrics (see ENVVAR_README.md)
* Improve robustness in handling rare core event overflows
* A few fixes for c_example
* Support using Linux perf API for core PMU for systems with offlined cores
* Add -i parameter to more tools
* support select metrics in virtual machines with vPMU support (e.g. AWS virtualized instances with arch_perfmon flag).
* pcm-memory: make -pmm/-pmem the default option on systems with PMM/PMem support
* pcm-tsx: update events for ICL and SKL, allow collection of up to 8 events
* pcm-raw: support fixed PMU counters
* fix UBOX MSR addresses for Jaketown/Ivytown
* support Icelake client CPUs
* new pcm-raw utility: to program arbitrary core and uncore events by specifying raw register event ID encoding
* pcm-memory: support -all option to show channels event if they do not have any traffic (inactive memory channels)
* pcm-memory: csv output for Near Memory hit rate (in PMem Memory Mode)
* pcm-memory: show memory channels with PMM but w/o DRAM DIMMs
* unfreeze counters using global uncore counter control register during uncore PMU initialization (some other tools freeze using global control before exit)