fix for unicorn-engine#2153

Currently svc $n always passes intno 2 to the hook, this PR should fix this.

Author: kittennbfive

qemu/accel/tcg/cpu-exec.c

@@ -397,6 +397,10 @@ static inline bool cpu_handle_exception(CPUState *cpu, int *ret)
 #if defined(TARGET_PPC)
         CPUPPCState *env = &(POWERPC_CPU(uc->cpu)->env);
         env->nip += 4;
+#endif
+#if defined(TARGET_ARM)
+        CPUARMState *env = &(ARM_CPU(uc->cpu)->env);
+        cpu->exception_index=env->exception.syndrome&0xff; //save svc call number so it will be passed to uc-hook
 #endif
         // Unicorn: call registered interrupt callbacks
         catched = false;