fix root path search

[christianrauch]

whereis searches for files:

$ whereis aarch64-linux-gnu-gcc 
aarch64-linux-gnu-gcc: /usr/bin/aarch64-linux-gnu-gcc /usr/share/man/man1/aarch64-linux-gnu-gcc.1.gz

Actually, we the script is looking for the executable aarch64-linux-gnu-gcc, which can be found with which instead of whereis.

Also, while the ROOT_PATH is determined via aarch64-linux-gnu-gcc the rest of the CMake files etc. assume the arm-linux-gnueabihf toolchain.

[dridri]

Actually I've never tried compiling for 64 bits target, does it work well ?

[christianrauch]

Well, I am still encountering issues with the Lua dependency and fixing them as well along the way.

[christianrauch]

I eventually managed to compile this on Ubuntu 24.04 without the pigpio library.