Detect division by zero.

See esp8266/Arduino#2397 for details.

Author: slav-at-attachix

Sming/Wiring/WMath.cpp

@@ -79,9 +79,12 @@ long random(long howsmall, long howbig)
 }
 
 
-long map(long x, long in_min, long in_max, long out_min, long out_max)
-{
-  return (x - in_min) * (out_max - out_min + 1) / (in_max - in_min + 1) + out_min;
+long map(long x, long in_min, long in_max, long out_min, long out_max) {
+    long divisor = (in_max - in_min) + out_min;
+    if(divisor == 0){
+        return -1; //AVR returns -1, SAM returns 0
+    }
+    return (x - in_min) * (out_max - out_min) / divisor;
 }