tcg/loongarch64: Add direct jump support

tcg/loongarch64: Add direct jump support

Similar to the ARM64, LoongArch has PC-relative instructions such as
PCADDU18I. These instructions can be used to support direct jump for
LoongArch. Additionally, if instruction "B offset" can cover the target
address(target is within ±128MB range), a single "B offset" plus a nop
will be used by "tb_target_set_jump_target".

Signed-off-by: Qi Hu <huqi@loongson.cn>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: WANG Xuerui <git@xen0n.name>
Message-Id: <20221015092754.91971-1-huqi@loongson.cn>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>