cpu-exec: Also reload CPUClass *cc after longjmp return in cpu_exec()

Local variable CPUClass *cc needs to be reloaded after return from longjmp,
too.  (This fixes a mips-softmmu crash observed on FreeBSD when QEMU is
built with clang.)
Reported-by: NDimitry Andric <dim@FreeBSD.org>
Signed-off-by: NJuergen Lock <nox@jelal.kn-bremen.de>
Signed-off-by: NAndreas Färber <afaerber@suse.de>

cpu-exec.c

@@ -681,6 +681,10 @@ int cpu_exec(CPUArchState *env)
              * local variables as longjmp is marked 'noreturn'. */
             cpu = current_cpu;
             env = cpu->env_ptr;
+#if !(defined(CONFIG_USER_ONLY) && \
+      (defined(TARGET_M68K) || defined(TARGET_PPC) || defined(TARGET_S390X)))
+            cc = CPU_GET_CLASS(cpu);
+#endif
         }
     } /* for(;;) */