Fix -Wmisleading-indentation false-positive

Fix -Wmisleading-indentation false-positive

gcc/c-family/ChangeLog:

	* c-indentation.c (should_warn_for_misleading_indentation):
	Float out and consolidate the calls to get_visual_column that
	are passed guard_exploc as an argument.  Compare
	next_stmt_vis_column with guard_line_first_nws instead of with
	body_line_first_nws.

gcc/testsuite/ChangeLog:

	* c-c++-common/Wmisleading-indentation.c: Augment test.

From-SVN: r228027