bug#29567: [PATCH] src/xterm.c: use 'thickness' only in a case of !USE_CAIRO

[Eli Zaretskii]

> From: Alexander Kuleshov <kuleshovmail@gmail.com>
> Date: Tue, 5 Dec 2017 00:11:47 +0600
> 
> I've attached simple patch with moving of the `thickness` var
> (from the x_draw_underwave() src/xterm.c) a little bit below, to get rid of:
> 
> xterm.c:3520:61: error: unused variable 'thickness' 
> [-Werror,-Wunused-variable]
>   int wave_height = 3 * scale_y, wave_length = 2 * scale_x, thickness = 
> scale_y;
> 
> as this variable is used only in a case of !USE_CAIRO

Thanks.  Did the patched source compile for you in the !USE_CAIRO
case?  Because 'thickness' needs to be declared as 'int' before it can
be used.

So I installed a slightly different change to avoid the warning.