Undo c85853, with explanation.

git-svn-id: https://svn.r-project.org/R/trunk@85867 00db46b3-68df-0310-9c12-caf00c1e9a41

share/texmf/tex/latex/Rd.sty

@@ -287,7 +287,10 @@
 % Rd2latex() should never let \Sexpr through to here.
 \newcommand\Sexpr[2][]{{\normalfont\texttt{\bsl Sexpr[#1]\{#2\}}}}
 
-\newcommand{\var}[1]{{\textsl{#1}}}
+% Texinfo 7.1 says that it is planned to change @var "in the next
+% release to use a variable-width, slanted roman font in all contexts"
+% as we apparently have done forever.
+\newcommand{\var}[1]{{\normalfont\textsl{#1}}}
 
 \newcommand{\dfn}[1]{\textsl{#1}}
 \let\Cite=\dfn