Footer conditioning should use \ifdim

[wgrundlingh]

In moderncvfooti.sty, the footer size is progressively checked against \footwidth. If it exceeds this length, a line break \\ is inserted. This check should be performed using \ifdim, not \ifnum:

\newcommand*{\addtofoot}[2][\footsymbol]{%
  \if@firstfootelement%
    \savebox{\foottempbox}{\usebox{\footbox}#2}%
  \else%
    \savebox{\foottempbox}{\usebox{\footbox}#1#2}\fi%
  \settowidth{\footboxwidth}{\usebox{\foottempbox}}%
  \ifnum\footboxwidth<\footwidth%  <---------------------------------
    \savebox{\footbox}{\usebox{\foottempbox}}%
    \@firstfootelementfalse%
  \else%
    \flushfoot\\%
    \savebox{\footbox}{#2}%
    \savebox{\foottempbox}{#2}%
    \settowidth{\footboxwidth}{\usebox{\footbox}}%
    \@firstfootelementfalse\fi}