c-family: Fix regression in location-overflow-test-1.c [PR97117]

c-family: Fix regression in location-overflow-test-1.c [PR97117]

The r11-3266 patch that added macro support to -Wmisleading-indentation
accidentally suppressed the column-tracking diagnostic in
get_visual_column in some cases, e.g. in the location-overflow-test-1.c
testcase.

More generally, when all three tokens are on the same line and we've run
out of locations with column info, then their location_t values will be
equal, and we exit early from should_warn_for_misleading_indentation due
to the new check

  /* Give up if the loci are not all distinct.  */
  if (guard_loc == body_loc || body_loc == next_stmt_loc)
    return false;

before we ever call get_visual_column.

[ This new check is needed to detect and give up on analyzing code
  fragments where exactly two out of the three tokens come from the same
  macro expansion, e.g.

    #define MACRO \
      if (a)      \
        foo ();

    MACRO; bar ();

  Here, guard_loc and body_loc will be equal and point to the macro
  expansion point (and next_stmt_loc will point to 'bar').  The heuristics
  that the warning uses are not really valid in scenarios like these.  ]

In order to restore the column-tracking diagnostic, this patch moves the
the diagnostic code out from get_visual_column to earlier in
should_warn_for_misleading_indentation.  Moreover, it tests the three
locations for a zero column all at once, which I suppose should make us
issue the diagnostic more consistently.

gcc/c-family/ChangeLog:

	PR testsuite/97117
	* c-indentation.c (get_visual_column): Remove location_t
	parameter.  Move the column-tracking diagnostic code from here
	to ...
	(should_warn_for_misleading_indentation): ... here, before the
	early exit for when the loci are not all distinct.  Don't pass a
	location_t argument to get_visual_column.
	(assert_get_visual_column_succeeds): Don't pass a location_t
	argument to get_visual_column.
	(assert_get_visual_column_fails): Likewise.