Add sun.misc.PerfCounter from OpenJDK 7.

openjdk/allsources.lst

@@ -11521,6 +11521,7 @@ sun/security/jgss/wrapper/SunNativeProvider.java
 @OPENJDK6@/jdk/src/share/classes/sun/misc/NativeSignalHandler.java
 @OPENJDK6@/jdk/src/share/classes/sun/misc/Perf.java
 @OPENJDK6@/jdk/src/share/classes/sun/misc/PerformanceLogger.java
+@OPENJDK7@/jdk/src/share/classes/sun/misc/PerfCounter.java
 @OPENJDK6@/jdk/src/share/classes/sun/misc/ProxyGenerator.java
 @OPENJDK6@/jdk/src/share/classes/sun/misc/Queue.java
 @OPENJDK6@/jdk/src/share/classes/sun/misc/REException.java

runtime/openjdk.cs

@@ -5741,7 +5741,11 @@ namespace IKVM.NativeCode.sun.misc
 
 		public static object createLong(object thisPerf, string name, int variability, int units, long value)
 		{
-			throw new NotImplementedException();
+#if FIRST_PASS
+			return null;
+#else
+			return global::java.nio.ByteBuffer.allocate(8);
+#endif
 		}
 
 		public static object createByteArray(object thisPerf, string name, int variability, int units, byte[] value, int maxLength)