* c.opt (Wdangling-else): New option.

	* c-parser.c (c_parser_if_statement): Replace OPT_Wparentheses with
	OPT_Wdangling_else.

	* parser.c (cp_parser_selection_statement): Replace OPT_Wparentheses
	with OPT_Wdangling_else.

	* doc/invoke.texi: Document -Wdangling-else.

	* c-c++-common/Wdangling-else-1.c: New test.
	* c-c++-common/Wdangling-else-2.c: New test.
	* c-c++-common/Wdangling-else-3.c: New test.

From-SVN: r235885