kernel/linux: prepare for arch whose kenel name is not the standard name

For some architectures, the kernel architecture name is not the common
name of the architecture for other tools.

For example: ARM 64-bit is commonly referenced as aarch64, but the kernel
calls it arm64.

Signed-off-by: Michael Hope <michael.hope@linaro.org>
Signed-off-by: Zhenqiang Chen <zhenqiang.chen@linaro.org>
[yann.morin.1998@free.fr: split out of the aarch64 patch]
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_64=y

 CT_ARCH_powerpc=y

 CT_KERNEL_linux=y

 CT_KERNEL_V_2_6_31=y

 CT_BINUTILS_V_2_20_1a=y

 CT_BINUTILS_FOR_TARGET=y

 CT_CC_V_4_5_2=y

 CT_CC_LANG_FORTRAN=y

 CT_CC_LANG_CXX=y

 CT_CC_LANG_JAVA=y

 CT_LIBC_glibc=y

 CT_LIBC_GLIBC_V_2_9=y

 # CT_LIBC_GLIBC_FORCE_UNWIND is not set

 CT_DEBUG_gdb=y

 CT_GDB_NATIVE=y

 CT_GMP_V_5_0_1=y

 CT_MPFR_V_3_0_0=y

 CT_CLOOG_V_0_15_10=y

 CT_MPC_V_0_8_2=y