HPCC-14572 Fix windows build break (function not defined)

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>

system/jlib/jfile.cpp

@@ -2134,6 +2134,12 @@ offset_t CFileAsyncIO::appendFile(IFile *file,offset_t pos,offset_t len)
     UNIMPLEMENTED; 
 }
 
+unsigned __int64 CFileAsyncIO::getStatistic(StatisticKind kind)
+{
+    //MORE: Could implement - but I don't think this class is currently used
+    return 0;
+}
+
 #ifdef _WIN32
 
 //-- Windows implementation -------------------------------------------------
@@ -2392,12 +2398,6 @@ offset_t CFileAsyncIO::size()
     return length;
 }
 
-unsigned __int64 CFileAsyncIO::getStatistic(StatisticKind kind)
-{
-    //MORE: Could implement - but I don't think this class is currently used
-    return 0;
-}
-
 size32_t CFileAsyncIO::read(offset_t pos, size32_t len, void * data)
 {
     CriticalBlock procedure(cs);