掌機 - Nintendo 3DS - 解決gcc.cc: undefined reference to host_detect_local_cpu(int, char const**)問題

參考資訊：
https://linaro-toolchain.linaro.narkive.com/mealwez3/cross-compilation-issue

問題如下：

$ g++ -no-pie   -g -O2   -DIN_GCC  -DCROSS_DIRECTORY_STRUCTURE   -fno-exceptions -fno-rtti -fasynchronous-unwind-tables -W -Wall -Wno-narrowing -Wwrite-strings -Wcast-qual -Wmissing-format-attribute -Woverloaded-virtual -pedantic -Wno-long-long -Wno-variadic-macros -Wno-overlength-strings   -DHAVE_CONFIG_H -static-libstdc++ -static-libgcc  -o xgcc gcc.o gcc-main.o ggc-none.o \
    c/gccspec.o  libcommon-target.a \
        libcommon.a ../libcpp/libcpp.a   ../libbacktrace/.libs/libbacktrace.a ../libiberty/libiberty.a ../libdecnumber/libdecnumber.a
    /usr/bin/ld: gcc.o: in function `.LANCHOR1':
    gcc.cc:(.rodata+0x58c): undefined reference to `host_detect_local_cpu(int, char const**)'
    collect2: error: ld returned 1 exit status
    make[1]: *** [Makefile:2172: xgcc] Error 1
    make[1]: Leaving directory 'buildscripts/.devkitARM/arm-none-eabi/gcc/gcc'
    make: *** [Makefile:4607: all-gcc] Error 2
    Error building gcc stage1

解法如下：

$ export CROSSBUILD=arm-linux-gnueabihf
$ ./build-devkit.sh

P.S. 如果在ARM CPU上面編譯devkitpro，需要指定CROSSBUILD