6839126: Type error found by newer windows compiler

Reviewed-by: never, kvn

src/share/vm/adlc/filebuff.hpp

@@ -73,7 +73,7 @@ class FileBuff {
 
   // This converts a pointer into the buffer to a file offset.  It only works
   // when the pointer is valid (i.e. just obtained from getline()).
-  long getoff(const char* s) { return _bufoff + (s - _buf); }
+  long getoff(const char* s) { return _bufoff + (long)(s - _buf); }
 };
 
 //------------------------------FileBuffRegion---------------------------------