PATCH: improve gprof error message

[Nick Clifton]

Hi Ben,

> 2006-03-21  Ben Elliston  <bje@au.ibm.com>
> 
>        * corefile.c (core_init): Report that the executable is not in the
>        expected executable format rather than "a.out" format.

Approved - please apply.

Cheers
   Nick