Fixed sidebar config sometime not increasing width

The sidebar has a numerical mimumum width that is statically defined,
and users may set the width of the sidebar in config by incrementing the
percentage of the screen between this minimum and a maximum value of
50%. However, internally the mimimum percentage could be set as low as
zero, and while that did not decrease the sidebar size below the
numerical minimum width, did mean that between 0 and the mimimum width
increasing the percentage had no visual effect to indicate change. Now
the mimimum percent is not decremented below the mimimum width.

Signed-off-by: Morgan Seltzer <MorganSeltzer000@gmail.com>
Signed-off-by: Lukas Fleischer <lfleischer@calcurse.org>

src/wins.c

@@ -229,7 +229,7 @@ void wins_sbar_winc(void)
 
 void wins_sbar_wdec(void)
 {
-	if (sbarwidth_perc > 0)
+	if (col * sbarwidth_perc / 100 > SBARMINWIDTH)
 		sbarwidth_perc--;
 }