[benchmark] Disable one benchmark when compiling on Linux.

I was able to run Benchmark_QuickCheck with the out of tree Linux build with
just these tests disabled and everything seems to work.

rdar://40541972

Author: gottesmm

benchmark/single-source/DataBenchmarks.swift

@@ -52,7 +52,7 @@ enum SampleKind {
 
 func sampleData(size: Int) -> Data {
     var data = Data(count: size)
-    data.withUnsafeMutableBytes { arc4random_buf($0, size) }
+    data.withUnsafeMutableBytes { getRandomBuf(baseAddress: $0, count: size) }
     return data
 }
 
@@ -89,11 +89,33 @@ func sampleString() -> Data {
     return Data(bytes: bytes)
 }
 
+#if os(Linux)
+import Glibc
+#endif
+
+@inline(__always)
+func getRandomBuf(_ arg: UnsafeMutableBufferPointer<UInt8>) {
+#if os(Linux)
+    getrandom(arg.baseAddress, arg.count, 0)
+#else
+    arc4random_buf(arg.baseAddress, arg.count)
+#endif
+}
+
+@inline(__always)
+func getRandomBuf(baseAddress: UnsafeMutablePointer<UInt8>, count: Int) {
+#if os(Linux)
+    getrandom(arg.baseAddress, arg.count, 0)
+#else
+    arc4random_buf(baseAddress, count)
+#endif
+}
+
 func sampleBridgedNSData() -> Data {
     let count = 1033
     var bytes = [UInt8](repeating: 0, count: count)
     bytes.withUnsafeMutableBufferPointer {
-        arc4random_buf($0.baseAddress, $0.count)
+        getRandomBuf($0)
     }
     let data = NSData(bytes: bytes, length: count)
     return Data(referencing: data)
@@ -151,7 +173,7 @@ func benchmark_AppendBytes(_ N: Int, _ count: Int, _ data_: Data) {
 func benchmark_AppendArray(_ N: Int, _ count: Int, _ data_: Data) {
     var bytes = [UInt8](repeating: 0, count: count)
     bytes.withUnsafeMutableBufferPointer {
-        arc4random_buf($0.baseAddress, $0.count)
+        getRandomBuf($0)
     }
     for _ in 1...10000*N {
         var data = data_

benchmark/single-source/DictionaryKeysContains.swift

@@ -37,17 +37,22 @@ public let DictionaryKeysContains = [
     runFunction: run_DictionaryKeysContains,
     tags: [.validation, .api, .Dictionary],
     setUpFunction: setup_DictionaryKeysContainsNative,
-    tearDownFunction: teardown_DictionaryKeysContains),
+    tearDownFunction: teardown_DictionaryKeysContains,
+    unsupportedPlatforms: [.linux]),
 ]
 #endif
 
 private var dictionary: [NSString: NSString]!
 
 private func setup_DictionaryKeysContainsNative() {
+#if os(Linux)
+  fatalError("Unsupported benchmark")
+#else
   let keyValuePairs = (1...1_000_000).map {
     ("\($0)" as NSString, "\($0)" as NSString)
   }
   dictionary = [NSString: NSString](uniqueKeysWithValues: keyValuePairs)
+#endif
 }
 
 #if _runtime(_ObjC)
@@ -68,9 +73,13 @@ private func teardown_DictionaryKeysContains() {
 
 @inline(never)
 public func run_DictionaryKeysContains(_ N: Int) {
+#if os(Linux)
+  fatalError("Unsupported benchmark")
+#else
   for _ in 0..<(N * 100) {
     CheckResults(dictionary.keys.contains("42"))
     CheckResults(!dictionary.keys.contains("-1"))
   }
+#endif
 }