drawops: Make de in do_circle() unsigned

"de" is never negative, so it should be unsigned.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
diff --git a/drawops/generic.c b/drawops/generic.c
index b3218f5..5c068e1 100644
--- a/drawops/generic.c
+++ b/drawops/generic.c
@@ -238,7 +238,7 @@
     u32 x1 = 0;
     u32 y1 = r;
     int d = 1-r;
-    int de = 3;
+    unsigned int de = 3;
     int dse = -2*r+5;
 
     do {