c:/cygwin64/home/windows/worker/jdkX-windows/build/src/java.base/windows/native/libnio/fs/WindowsNativeDispatcher.c(1069) : error C2065: 'SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE' : undeclared identifier
make[3]: *** [Lib-java.base.gmk:72: /cygdrive/c/cygwin64/home/windows/worker/jdkX-windows/build/build/windows-x86_64-server-fastdebug/support/native/java.base/libnio/WindowsNativeDispatcher.obj] Error 1
make[3]: *** Waiting for unfinished jobs....
make[2]: *** [make/Main.gmk:215: java.base-libs] Error 2

I think we need to check that identifier is available.