Support hardware counters (instructions, cache misses, ...) (#983)

* Add hardware counters to JSON exports

* Clarify Linux hardware counter setup

Cargo.lock

@@ -393,6 +393,7 @@ dependencies = [
  "libc",
  "nix",
  "once_cell",
+ "perf-event-open-sys",
  "platform-info",
  "predicates",
  "rand 0.10.3",
@@ -539,6 +540,15 @@ version = "1.70.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "384b8ab6d37215f3c5301a95a4accb5d64aa607f1fcb26a11b5303878451b4fe"
 
+[[package]]
+name = "perf-event-open-sys"
+version = "6.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a5f8d1487a4ffa23c80a1c355dd27235f9b66fb71ba0f261eb417e4fe8451347"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "platform-info"
 version = "2.2.0"