I got distracted from this for a little while...  Here is a final 
version with something in the texi file as well.

ChangeLog:

2002-03-12  James Ingham <jingham@apple.com>

         * cp-abi.c (set_cp_abi_cmd, show_cp_abi_cmd,): New functions,
         allow you to set & show cplus abi's in case gdb gets it wrong.
         (set_cp_abi_as_auto_default): New function, set the "auto" abi
         to be this abi.
         (is_cp_abi_auto_p): New function, say whether the current abi
         is the default or not.
         (_initialize_cp_abi): Define the cp-abi switching commands.
         * cp-abi.h: declare the new functions.
         * minsyms.c (install_minimal_symbols): don't switch the cp_abi
         unless the current abi is auto.
         * gnu-v2-abi.c (_initialize_gnu_v2_abi): don't switch to gnu-v2,
         but set it as the auto_default instead.

Okay to check in?