cpu: Define ArchCPU

For all targets, do this just before including exec/cpu-all.h.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

target/hppa/cpu.h

@@ -231,6 +231,7 @@ static inline HPPACPU *hppa_env_get_cpu(CPUHPPAState *env)
 #define ENV_OFFSET      offsetof(HPPACPU, env)
 
 typedef CPUHPPAState CPUArchState;
+typedef HPPACPU ArchCPU;
 
 #include "exec/cpu-all.h"