next: set rustup/cargo home dirs

As pre_tf_build() call hook is invoked from within a subshell,
environment variables are lost on calling it. Use set_hook_var to set
the {RUSTUP,CARGO}_HOME vars required by cargo/rustup.

Change-Id: Ibb8bcb08e60c4ff08b945861e3bd3f968bbcfad2
Signed-off-by: Zachary Leaf <zachary.leaf@arm.com>
1 file changed