tcg-alpha: Convert to CONFIG_QEMU_LDST_OPTIMIZATION

Signed-off-by: Richard Henderson <rth@twiddle.net>
tcg-alpha: Introduce TCG_REG_TB

Signed-off-by: Richard Henderson <rth@twiddle.net>
tcg-alpha: Set code_gen_buffer size

Signed-off-by: Richard Henderson <rth@twiddle.net>