complibs: disable building shared libs

Managing the shared version of the companion libraries
has become cumbersome.

Also, it will one day be possible to use the companion
libraries from the host distribution, and then we will
be able to easily use either shared or static libs.

As a side note, while working on the canadian-rework
series, it has become quite more complex to properly
handle shared companion libraries, as they need to be
built both for the build and gost systems. That's not
easy to handle. At all.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

# Options specific to crosstool-NG acting as a backend

config IS_A_BACKEND

    string

    option env="CT_IS_A_BACKEND"

config BACKEND

    bool

    default y if IS_A_BACKEND =  "y" || IS_A_BACKEND =  "Y"

    default n if IS_A_BACKEND != "y" && IS_A_BACKEND != "Y"

config BACKEND_ARCH

    string

    option env="CT_BACKEND_ARCH"

config BACKEND_KERNEL

    string

    option env="CT_BACKEND_KERNEL"

config BACKEND_LIBC

    string

    option env="CT_BACKEND_LIBC"