[committed] Add missing @cindex (PR c/60988)

[Marek Polacek]

transparent_union was missing a @cindex entry.  Tested with
info ./gcc/doc/gcc.info --index-search=transparent_union

Committed as obvious.

2014-06-10  Marek Polacek  <polacek@redhat.com>

	PR c/60988
	* doc/extend.texi: Add cindex for transparent_union.

diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index 23a7809..42db985 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -5732,6 +5732,8 @@ You may only specify this attribute on the definition of an @code{enum},
 also define the enumerated type, structure or union.
 
 @item transparent_union
+@cindex @code{transparent_union} attribute
+
 This attribute, attached to a @code{union} type definition, indicates
 that any function parameter having that union type causes calls to that
 function to be treated in a special way.

	Marek