libdpkg: Mention (^Z) instead of char for the MSDOS end of file character

Let's not use unneeded abbreviations, but in this case instead of just
expanding “char”, we'll say “(^Z)” like in the other error message
instance.

debian/changelog

@@ -213,6 +213,7 @@ dpkg (1.18.0) UNRELEASED; urgency=low
     - Fix error messages on invalid uid/git/mode command-line syntax errors
       in dpkg-statoverride, to not say they are from the statoverride file.
     - Fix error message on empty dsc file in dpkg-genchanges.
+    - Mention “(^Z)” instead of “char” for the MSDOS end of file character.
 
   [ Raphaël Hertzog ]
   * Drop myself from Uploaders.

lib/dpkg/parse.c

@@ -659,7 +659,7 @@ parse_stanza(struct parsedb_state *ps, struct field_state *fs,
       parse_error(ps, _("end of file before value of field '%.*s' (missing final newline)"),
                   fs->fieldlen, fs->fieldstart);
     if (c == MSDOS_EOF_CHAR)
-      parse_error(ps, _("MSDOS end of file char in value of field '%.*s' (missing newline?)"),
+      parse_error(ps, _("MSDOS end of file (^Z) in value of field '%.*s' (missing newline?)"),
                   fs->fieldlen, fs->fieldstart);
 
     blank_line = false;