File fix-build.patch of Package uranium-firmware-lulzbot

diff --git a/Marlin/Makefile b/Marlin/Makefile
index 9e9eeb42f..cc2aafc0b 100644
--- a/Marlin/Makefile
+++ b/Marlin/Makefile
@@ -470,8 +470,8 @@ LST = $(ASRC:.S=.lst) $(CXXSRC:.cpp=.lst) $(SRC:.c=.lst)
 
 # Combine all necessary flags and optional flags.
 # Add target processor to flags.
-ALL_CFLAGS = -mmcu=$(MCU) -I. $(CFLAGS)
-ALL_CXXFLAGS = -mmcu=$(MCU) $(CXXFLAGS)
+ALL_CFLAGS = -mmcu=$(MCU) -I. $(CFLAGS) -I/usr/avr/sys-root/include/
+ALL_CXXFLAGS = -mmcu=$(MCU) $(CXXFLAGS) -I/usr/avr/sys-root/include/
 ALL_ASFLAGS = -mmcu=$(MCU) -x assembler-with-cpp $(ASFLAGS)
 
 # set V=1 (eg, "make V=1") to print the full commands etc.