Fixing ATmega8 breakage from flush() change. (WestFW)

http://code.google.com/p/arduino/issues/detail?id=1019

hardware/arduino/cores/arduino/HardwareSerial.h

@@ -81,6 +81,15 @@ class HardwareSerial : public Stream
   extern HardwareSerial Serial3;
 #endif
 
+/*
+ * on ATmega8, the uart and its bits are not numbered, so there is no "TXC0"
+ * definition.  It is slightly cleaner to define this here instead of having
+ * conditional code in the cpp module.
+ */
+#if !defined(TXC0)
+#define TXC0 TXC
+#endif
+
 extern void serialEventRun(void) __attribute__((weak));
 
 #endif