Can you download the 64bit toolchain from FW R9?
https://source.sierrawireless.com/resources/airprime/software/wp76xx/wp76xx-firmware-release-9-components/#sthash.c1Pa64qx.dpbs
Install it to /opt/swi/y22-ext folder.
After that you can compile the application by
/opt/swi/y22-ext/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-gcc -o HelloFuji ./hello.c