preprocessor/100142 - revert unwanted change in last commit

This reverts a s/column_offset/column/ change in the fix for PR99446.

2021-04-19  Richard Biener  <rguenther@suse.de>

	PR preprocessor/100142
libcpp/
	* line-map.c (linemap_position_for_loc_and_offset): Revert
	unintended s/column_offset/column/ change.

gcc/testsuite/
	* gcc.dg/pr100142.c: New testcase.
	* g++.dg/diagnostic/pr72803.C: Revert last change.