Merge pull request jruby#9347 from headius/jdk_flock_windows

Use JDK for File#flock on Windows

Author: headius

core/src/main/java/org/jruby/util/io/PosixShim.java

@@ -216,7 +216,8 @@ public int flock(ChannelFD fd, int lockMode) {
 
         int real_fd = fd.realFileno;
 
-        if (posix.isNative() && real_fd != -1 && real_fd < FilenoUtil.FIRST_FAKE_FD && !Platform.IS_SOLARIS) {
+        if (!Platform.IS_SOLARIS && !Platform.IS_WINDOWS &&
+                posix.isNative() && real_fd != -1 && real_fd < FilenoUtil.FIRST_FAKE_FD) {
             // we have a real fd and not on Solaris...try native flocking
             // see jruby/jruby#3254 and jnr/jnr-posix#60
             int result = posix.flock(real_fd, lockMode);