internals: fix stripping yet once again

Fix typo introduced by changeset #055e505f28be.
Also, handle older versions of gcc (typically, all versions
prior to 4.0.0).

Maxime provided a similar patch, missing the case for the
legacy versions of gcc.

Reported-by: Maxime Bizon <mbizon@freebox.fr>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

# Linux kernel options

config KERNEL_linux

    select KERNEL_SUPPORTS_SHARED_LIBS

    help

      Build a toolchain targeting systems running Linux as a kernel.