Fixed corner-case rounding in int.__floordiv__

Author: otethal

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/ints/IntBuiltins.java

@@ -408,7 +408,7 @@ int doLPiOvf(int left, PInt right) {
             try {
                 return Math.floorDiv(left, right.intValueExact());
             } catch (ArithmeticException e) {
-                return 0;
+                return left < 0 == right.isNegative() ? 0 : -1;
             }
         }
 
@@ -424,7 +424,7 @@ long doLPiOvf(long left, PInt right) {
             try {
                 return Math.floorDiv(left, right.longValueExact());
             } catch (ArithmeticException e) {
-                return 0;
+                return left < 0 == right.isNegative() ? 0 : -1;
             }
         }