Fix the info-dir line for the com_err.texinfo file

Fix the info-dir line for the com_err.texinfo file

Fix the info-dir line so that the menu name does not contain a .info
prefix.  First of all, it's ugly, secondly, it causes the install-info
command to fail to remove the com_err info file from the
/usr/share/info/dir file when the comerr-dev package is removed and
purged.

Addresses Debian Bug: #401711

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>