Latest Marlin on Printrboard: Problems! (no replies)

Downloaded latest Marlin (1.1.1). Compiling with Arduino 1.8.2 at Teensy2++. I've set Motherboard to Board_Printrboard (with appropriate caps). Here are examples of the two errors:

In file included from /tmp/arduino_build_805673/sketch/pins.h:115:0,
from /tmp/arduino_build_805673/sketch/MarlinConfig.h:33,
from /tmp/arduino_build_805673/sketch/G26_Mesh_Validation_Tool.cpp:27:
/tmp/arduino_build_805673/sketch/pins_PRINTRBOARD.h:40:0: warning: "USBCON" redefined
#define USBCON 1286 // Disable MarlinSerial etc.
^
In file included from /home/jim/arduino-1.8.2/hardware/tools/avr/avr/include/avr/iousb1286.h:38:0,
from /home/jim/arduino-1.8.2/hardware/tools/avr/avr/include/avr/io.h:192,
from /tmp/arduino_build_805673/sketch/fastio.h:31,
from /tmp/arduino_build_805673/sketch/MarlinConfig.h:26,
from /tmp/arduino_build_805673/sketch/G26_Mesh_Validation_Tool.cpp:27:
/home/jim/arduino-1.8.2/hardware/tools/avr/avr/include/avr/iousbxx6_7.h:963:0: note: this is the location of the previous definition
#define USBCON _SFR_MEM8(0XD8)

^
(There are many repeats of this same error, just in different files.)

In file included from /tmp/arduino_build_805673/sketch/serial.cpp:23:0:
serial.h: In function 'void serialprintPGM(const char*)':
serial.h:35: error: 'customizedSerial' was not declared in this scope
#define MYSERIAL customizedSerial
^
/tmp/arduino_build_805673/sketch/serial.h:96:42: note: in expansion of macro 'MYSERIAL'
while (char ch = pgm_read_byte(str++)) MYSERIAL.write(ch);
^
serial.cpp: In function 'void serial_echopair_P(const char*, const char*)':

(There are several of this flavor also.)


Bottom line: The errors seem to be related to USBCON having two definitions and to customizedSerial not being defined.

My assumption was that a new version of something as major as Marlin would be tested enough to at least compile cleanly for a version like the Printrboard. So I expect that I'm doing something very wrong.
Does anyone have any suggestions?

TIA!