samples: update to latest set of options

Update all the samples, so that there is not config-prompt when
recalling samples. This is no upgrade, it's just about having
new options set (y or n) in the samples.

Also, get rid of the armeb-test_nptl-linux-uclibcgnueabi, it's no
longer needed, there's a non-test sample with uClibc NPTL, now.

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"

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"