Add experimental Swift standard library support for tracking the invocations of runtime functions

It allows for collecting the state of runtime function counters, which are used to determine how many times a given runtime function was called.

It is possible to get the global counters, which represent the total number of invocations, or per-object counters, which represent the number of runtime functions calls for a specific object.

Author: swiftix

stdlib/public/core/CMakeLists.txt

@@ -107,6 +107,7 @@ set(SWIFTLIB_ESSENTIAL
   REPL.swift
   Reverse.swift
   Runtime.swift.gyb
+  RuntimeFunctionCounters.swift
   SipHash.swift.gyb
   SentinelCollection.swift
   Sequence.swift

stdlib/public/core/GroupInfo.json

@@ -164,6 +164,7 @@
     "Print.swift",
     "REPL.swift",
     "Runtime.swift",
+    "RuntimeFunctionCounters.swift",
     "Shims.swift",
     "ThreadLocalStorage.swift",
     "Unmanaged.swift",