Make parse.h C++ safe by avoiding "or" keyword

Fixes for g++ (4.7.2) following compiler errors when fio.h
gets included (e.g. in an external C++ ioengine):

--8<---
[...]
parse.h:31:6: error: expected unqualified-id before ‘or’ token
[...]
--->8---

Signed-off-by: Daniel Gollub <d.gollub@telekom.de>

Updated by me to apply to recent version, and fix gfio usage
of ->or as well.

Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/parse.h b/parse.h
index 8eefff9..5273d23 100644
--- a/parse.h
+++ b/parse.h
@@ -28,7 +28,7 @@
 	const char *ival;		/* string option */
 	unsigned int oval;		/* output value */
 	const char *help;		/* help text for sub option */
-	int or;				/* OR value */
+	int orval;			/* OR value */
 	void *cb;			/* sub-option callback */
 };