libc/{glibc,eglibc}: Don't download glibc-ports when not available

Don't download glibc-ports when glibc or eglibc version greater than 2.16,
because the "ports" source is mainline in the glibc or eglibc since version 2.17.

Signed-off-by: "Daniel Zimmermann" <netzimme@gmail.com>
Message-Id: <9c045ca3cf1b9dc89da3.1384602843@haus-VirtualBox>
Patchwork-Id: 291766
[yann.morin.1998@free.fr: slightly tweak subject, change variable name]
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>

CT_EXPERIMENTAL=y

CT_LOCAL_TARBALLS_DIR="${HOME}/src"

CT_SAVE_TARBALLS=y

CT_LOG_EXTRA=y

CT_ARCH_m68k=y

CT_KERNEL_linux=y

CT_KERNEL_V_3_5=y

CT_BINUTILS_V_2_21_1a=y

CT_LIBC_UCLIBC_CONFIG_FILE="${CT_LIB_DIR}/samples/${CT_TARGET}/${CT_LIBC}-${CT_LIBC_VERSION}.config"

CT_THREADS_LINUXTHREADS=y