glibc: Compile using thumb2 for arch > armv5 if user chooses
For arm we enforce ARM mode regardless of ARM_INSTRUCTION_SET
choice from config metadata, glibc works fine with thumb2 for
armv7+ so limit the restriction to armv5 and lower, tested on
rpi3 works equally well as arm mode glibc and sheds about 0.5MB
in size for main package alone. Other glibc build packages also
gets smaller
ARM: 2696 KiB libc6
Thumb2: 2132 KiB libc6
Signed-off-by: Khem Raj <raj.khem@gmail.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
