I'm not sure that what you need is possible. I think that "line_regex" is used when the filename and line number on the build output are on separate lines, so it will match the line_regex and then start going backwards to find the filename using file_regex.
If the filename and line number are on the same line then you're only supposed to use file_regex and use the match groups to parse out the info. The problem is that Sublime seems to expect that the filename is always before the line number. Group 0 is the filename, 1 is the line number, 2 is the column, and 3 is the error message. There doesn't seem to be a way of telling Sublime to use a different order though.
A Google search brought up some older posts with people having this very issue... no solution that I could find unfortunately.