Clean up gdb.c++ tests for dwarf 1

[Michael Elizabeth Chastain <mec@shout.net>]

gdb HEAD%20030205 has loads of this stuff in the C++ test suite:

  setup_xfail_format "DWARF 1"

There are 81 instances of this.

Some test scripts have them, and some don't.  I'd like to get rid
of them and replace them with something more coherent -- or nothing.

I see four choices.

(1) Just remove these calls to setup_xfail_format.  If someone runs the
    gdb test suite with DWARF 1, the test suite will do its job and give
    FAIL results for all the C++ tests that do not work with DWARF 1.

(2) Change the tests so that each C++ test script reports a single
    UNSUPPORTED for the whole script (if the debug format is DWARF 1).
    
    This requires about five lines of code per script.  This cannot be
    centralized in 'skip_cplus_tests', because the check for the debug
    format has to happen after the test script has compiled the test
    program, started gdb, and proceeded to main, so that 'info source'
    works.

(3) Leave the mess alone.

(4) Start fixing the DWARF 1 support.  I'll start testing DWARF 1 and
    filing bug reports for the things that don't work.

My preference order is (1) - (2) - (3) - (4).

What do you think?

Michael C