pixmap: omitting curly braces considered harmful

The break being outside of the else block effectively made an if clause
out of the while loop. This caused long hostnames to not be shortened
sufficiently which subsequentely made strcpy() write beyond buffer
boundaries.

backend/pixma_bjnp.c

@@ -367,9 +367,11 @@ determine_scanner_serial (const char *hostname, const char * mac_address, char *
           *dot = '\0';
         }
       else
+        {
           strcpy(copy, mac_address);
           break;
         }
+    }
   strcpy( serial, copy );
   return serial;
 }