FR: handle alternative formatting (assert when no caret found)

[GitMensch]

the default output of gcc and friends is as follows

    4 |     return e_rrno;
      |            ^~~~~~

which is nicely handled.

But there is also an alternative formatting for "complete line" that use a "bigger than" sign:

    3 |   {
    4 >     return e_rrno;
    5 |   }

which aborts with

 * Post-process module (cobc) failure due AssertionError exception:
 *   outproc/pp/gcc.py:347: at _handle_compile_line
 *     assert self.prev_line is None

Can you adjust the parser to handle that as well?