Fix description

(cherry picked from commit 5a6d4231)
Signed-off-by: Christophe Mutricy <xtophe@videolan.org>

configure.ac

@@ -4422,7 +4422,7 @@ AC_SUBST(DEFS_BIGENDIAN)
 dnl
 dnl Where to install KDE solid .desktop
 dnl
-AC_ARG_VAR([KDE4_CONFIG], [path to kde4-config utility])
+AC_ARG_VAR([KDE4_CONFIG], [kde4-config utility])
 AS_IF([test "x$KDE4_CONFIG" = "x"], [
   KDE4_CONFIG="kde4-config"
 ])