extend.texi: Document C++ restricted pointers and references.

extend.texi: Document C++ restricted pointers and references.

	* extend.texi: Document C++ restricted pointers and references.

	* cp-tree.h (grok_method_quals): Return this pointer qualifiers.
	* decl.c (grokdeclarator): Adjust calls to grok_method_quals.
	* decl2.c (grok_method_quals): Accept `restrict' as applying to
	the object pointer. Return such qualifiers.
	(grokclassfn): Apply this pointer qualifiers. Cleanup unused
	variables.

From-SVN: r30587