[noescape by default] Fix benchmarks and incorporate feedback

Adds @escaping to internal benchmark code to fix it. References SR for
known limitation. Use stdlib coding style for arguments.

Author: milseman

benchmark/single-source/Integrate.swift

@@ -20,7 +20,7 @@ class Integrate {
 
   let fun: (Double) -> Double
 
-  init (f: (Double) -> Double) {
+  init (f: @escaping (Double) -> Double) {
     fun = f
   }
 

benchmark/utils/DriverUtils.swift

@@ -50,7 +50,7 @@ struct Test {
   let index: Int
   let f: (Int) -> ()
   var run: Bool
-  init(name: String, n: Int, f: (Int) -> ()) {
+  init(name: String, n: Int, f: @escaping (Int) -> ()) {
     self.name = name
     self.index = n
     self.f = f

test/IDE/complete_override.swift

@@ -463,7 +463,7 @@ class TestClassWithThrows : HasThrowing, HasThrowingProtocol {
 // HAS_THROWING: Begin completions
 // HAS_THROWING-DAG: Decl[InstanceMethod]/Super:         func foo() throws {|}; name=foo() throws
 // HAS_THROWING-DAG: Decl[InstanceMethod]/Super:         override func bar() throws {|}; name=bar() throws
-// FIXME: make the below require to print @escaping
+// FIXME: SR-2214 make the below require printing @escaping 
 // HAS_THROWING-DAG: Decl[InstanceMethod]/Super:         override func baz(x: {{(@escaping )?}}() throws -> ()) rethrows {|}; name=baz(x: {{(@escaping )?}}() throws -> ()) rethrows
 // HAS_THROWING-DAG: Decl[Constructor]/Super:            init() throws {|}; name=init() throws
 // HAS_THROWING: End completions

validation-test/stdlib/HashingAvalanche.swift

@@ -8,8 +8,11 @@ import StdlibUnittest
 
 var HashingTestSuite = TestSuite("Hashing")
 
-func avalancheTest(_ bits: Int, _ hashUnderTest: @escaping (UInt64) -> UInt64, 
-                   _ pValue: Double) {
+func avalancheTest(
+  _ bits: Int,
+  _ hashUnderTest: @escaping (UInt64) -> UInt64,
+  _ pValue: Double
+) {
   let testsInBatch = 100000
   let testData = randArray64(testsInBatch)
   let testDataHashed = Array(testData.lazy.map { hashUnderTest($0) })