Use the regular arduino core

Previously, the pinoccio boards used an older copy of the regular
arduino core that is included in this repository. By explicitely listing
the core as "arduino:arduino" (instead of the previous implicit
pinoccio:arduino"), it uses the arduino core from the hardware/arduino
folder, i.e., the regular arduino core.

The variant folder is still taken ofr the hardware/pinoccio/variants
folder as before.

Author: matthijskooijman

hardware/pinoccio/avr/boards.txt

@@ -18,7 +18,7 @@ pinoccio.bootloader.lock_bits=0x0F
 
 pinoccio.build.mcu=atmega256rfr2
 pinoccio.build.f_cpu=16000000L
-pinoccio.build.core=arduino
+pinoccio.build.core=arduino:arduino
 pinoccio.build.variant=pinoccio
 pinoccio.build.board=PINOCCIO
 
@@ -42,6 +42,6 @@ pinoccio128.bootloader.lock_bits=0x0F
 
 pinoccio128.build.mcu=atmega128rfa1
 pinoccio128.build.f_cpu=16000000L
-pinoccio128.build.core=pinoccio
+pinoccio128.build.core=arduino:arduino
 pinoccio128.build.variant=pinoccio
 pinoccio.build.board=PINOCCIO