/usr/bin/arm-none-eabi-gcc-5.4.1 is in gcc-arm-none-eabi 15:5.4.1+svn241155-1.
This file is owned by root:root, with mode 0o755.
It is a symlink to /usr/bin/./usr/bin/arm-none-eabi-gcc
/usr/bin/./usr/bin/arm-none-eabi-gcc