Commit d30a1ad0 translated the symbol file checker from perl to
python by doing a literal translation in most cases. Unfortunately one
string formatting operation was not really translated into python
leaving users with non-helpful error:

'Symbol $1 is listed twice'
Signed-off-by: NPeter Krempa <pkrempa@redhat.com>
Reviewed-by: NErik Skultety <eskultet@redhat.com>
Reviewed-by: NMichal Privoznik <mprivozn@redhat.com>

Signed-off-by: NJán Tomko <jtomko@redhat.com>
Reviewed-by: NDaniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: NErik Skultety <eskultet@redhat.com>

As part of a goal to eliminate Perl from libvirt build tools,
rewrite the check-symfile.pl tool in Python.

This was a straight conversion, manually going line-by-line to
change the syntax from Perl to Python. Thus the overall structure
of the file and approach is the same.
Tested-by: NCole Robinson <crobinso@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>