added -DDEBUG_OUTPUT=Serial for workaround not defined in Library

esp8266/Arduino#2279

Author: lebeno

Makefile

@@ -16,7 +16,7 @@ HWTYPE = esp8266
 ESPTOOL = $(ARDUINO15_PATH)/packages/$(HWTYPE)/tools/esptool/0.4.9/esptool
 CTAGS = $(ARDUINO_PATH)/tools-builder/ctags/5.8-arduino10
 
-CXX_FLAGS := -DDEBUG
+CXX_FLAGS := -DDEBUG  -DDEBUG_OUTPUT=Serial
 PREFS = --prefs=build.debug_level="$(CXX_FLAGS)" --prefs=tools.ctags.path="$(CTAGS)"
 
 SKETCHES = $(find $(CURDIR) -name *.ino)
@@ -62,4 +62,4 @@ monitor:
 #	stty -F $(SERIAL_PORT) ispeed $(SERIAL_BAUD) ospeed $(SERIAL_BAUD) cs8 -cstopb parenb
 #	stty -F $(SERIAL_PORT) ispeed $(SERIAL_BAUD) ospeed $(SERIAL_BAUD)
 	stty <$(SERIAL_PORT)
-	screen $(SERIAL_PORT) $(SERIAL_BAUD),cs8,-ixon,-ixoff,-istrip
+	screen $(SERIAL_PORT) $(SERIAL_BAUD),cs8,-ixon,-ixoff,-istrip