arch: allow adding a suffix to the arch-part of a tuple

For some architectures, it is legit to have an alternate value in the
'architecture' part of the tuple. For example:
armv5te-*
armv7a8-*

Besides, some packages expect the tuple to reflect the arch variant
(eg. openMPI) to detect the variant's capabilities (eg. atomic
primitives).

This patch adds an option for the user to specify a suffix to be added
to the arch-part of the tuple.

Signed-off-by: Willy Tarreau <w@1wt.eu>
Message-ID: <20130120225822.GS6838@1wt.eu>
Patch-Id: 213994
[yann.morin.1998@free.fr: make it a suffix, not an override]
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_CPU="cortex-m3"

CT_ARCH_TUNE="cortex-m3"

CT_ARCH_FLOAT_SW=y

CT_ARCH_arm=y

# CT_ARCH_USE_MMU is not set

CT_ARCH_ARM_MODE_THUMB=y

CT_TARGET_VENDOR="bare_newlib_cortex_m3_nommu"

CT_ARCH_BINFMT_FLAT=y

CT_BINUTILS_V_2_19_1a=y

CT_CC_V_4_4_1=y

CT_CC_LANG_CXX=y

CT_LIBC_NEWLIB_V_1_18_0=y

CT_GMP_V_4_3_2=y

CT_MPFR_V_2_4_2=y

CT_PPL_V_0_10_2=y

CT_CLOOG_V_0_15_9=y