Wire: fix for targets without slave support

Author: facchinm

libraries/Wire/Wire.cpp

@@ -7,26 +7,32 @@ void arduino::MbedI2C::begin() {
 }
 
 void arduino::MbedI2C::begin(uint8_t slaveAddr) {
+#ifdef DEVICE_I2CSLAVE
 	slave = new mbed::I2CSlave((PinName)_sda, (PinName)_scl);
 	slave->address(slaveAddr);
+#endif
 }
 
 void arduino::MbedI2C::end() {
 	if (master != NULL) {
 		delete master;
 	}
+#ifdef DEVICE_I2CSLAVE
 	if (slave != NULL) {
 		delete slave;
 	}
+#endif
 }
 
 void arduino::MbedI2C::setClock(uint32_t freq) {
 	if (master != NULL) {
 		master->frequency(freq);
 	}
+#ifdef DEVICE_I2CSLAVE
 	if (slave != NULL) {
 		slave->frequency(freq);
 	}
+#endif
 }
 
 void arduino::MbedI2C::beginTransmission(uint8_t address) {

libraries/Wire/Wire.h

@@ -52,7 +52,10 @@ class MbedI2C : public HardwareI2C
     virtual int available();
 
 private:
+
+#ifdef DEVICE_I2CSLAVE
     mbed::I2CSlave* slave;
+#endif
     mbed::I2C*      master;
     int _sda;
     int _scl;
@@ -68,3 +71,5 @@ extern arduino::MbedI2C Wire;
 #elif DEVICE_I2C > 1
 extern arduino::MbedI2C Wire1;
 #endif
+
+typedef arduino::MbedI2C TwoWire;