Add the filename/fd and invalid value to stat_struc_to_py error messages.
Add the filename/fd and invalid value to stat_struc_to_py error messages.

Thanks to Nathan Bird <ecthellion@gmail.com> for the initial report.

Signed-off-by: Rob Browning <1dc5917c2adeeba13d1ef33dbb40691a1b67cc65@defaultvalue.org>
Reviewed-by: Zoran Zaric <d7dacae2c968388960bf8970080a980ed5c5dcb7@zoranzaric.de>

apenwarr/bup,ToxicFrog/bup,gevaerts/bup,mhoeher/bup,gevaerts/bup,gevaerts/bup,pombredanne/bup,tjanez/bup,pombredanne/bup,jbaber/bup,mhoeher/bup,tjanez/bup,ToxicFrog/bup,jbaber/bup,pombredanne/bup,mhoeher/bup,apenwarr/bup,jbaber/bup,tjanez/bup,gevaerts/bup,jbaber/bup,mhoeher/bup,apenwarr/bup,mhoeher/bup,jbaber/bup,pombredanne/bup,mhoeher/bup,apenwarr/bup,ToxicFrog/bup,ToxicFrog/bup,jbaber/bup,tjanez/bup,tjanez/bup,pombredanne/bup,tjanez/bup,gevaerts/bup,ToxicFrog/bup,pombredanne/bup