toplev.c (flag_if_conversion, [...]): New static variables.

	* toplev.c (flag_if_conversion, flag_if_conversion2): New static
	variables.
	(lang_independent_options): Add -fif-conversion, -fif-conversion2
	(rest_of_compilation): Do if conversion only when asked for.
	(parse_options_and_default_flags): Set new variables to 1 for -O1
	* invoke.texi (-fif-conversion, -fif-conversion2): Document.

From-SVN: r52891