target/loongarch: Implement LSX fpu arith instructions

This patch includes:
- VF{ADD/SUB/MUL/DIV}.{S/D};
- VF{MADD/MSUB/NMADD/NMSUB}.{S/D};
- VF{MAX/MIN}.{S/D};
- VF{MAXA/MINA}.{S/D};
- VFLOGB.{S/D};
- VFCLASS.{S/D};
- VF{SQRT/RECIP/RSQRT}.{S/D}.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Song Gao <gaosong@loongson.cn>
Message-Id: <20230504122810.4094787-34-gaosong@loongson.cn>

target/loongarch/internals.h

@@ -53,6 +53,7 @@ void G_NORETURN do_raise_exception(CPULoongArchState *env,
 
 const char *loongarch_exception_name(int32_t exception);
 
+int ieee_ex_to_loongarch(int xcpt);
 void restore_fp_status(CPULoongArchState *env);
 
 #ifndef CONFIG_USER_ONLY