In the description of gcvt, add missing closing parenthesis in the
comparison with sprintf.
* manual/arith.texi (gcvt): Add missing closing parenthesis.
@c gcvt calls sprintf, that ultimately calls vfprintf, which malloc()s
@c args_value if it's too large, but gcvt never exercises this path.
@code{gcvt} is functionally equivalent to @samp{sprintf(buf, "%*g",
-ndigit, value}. It is provided only for compatibility's sake. It
+ndigit, value)}. It is provided only for compatibility's sake. It
returns @var{buf}.
If @var{ndigit} decimal digits would exceed the precision of a