Add spcial-case measure function for Android to work around large standard deviation on emulator (swiftlang/swift-corelibs-xctest#506)

Author: marcprux

Tests/CBORDecoderTests.swift

@@ -202,3 +202,20 @@ class CBORDecoderTests: XCTestCase {
         }
     }
 }
+
+#if os(Android)
+
+extension XCTestCase {
+    /// XCTestCase.measure on Android is problematic because
+    /// the emulator on a virtualized runner can be quite slow
+    /// but there is no way to set the standard deviation threshold
+    /// for failure, so we override it to simply run the block
+    /// and not perform any measurement.
+    /// 
+    /// See: https://github.com/swiftlang/swift-corelibs-xctest/pull/506
+    func measure(_ count: Int = 0, _ block: () -> ()) {
+        block()
+    }
+}
+#endif
+