cpu: Move cpu_index field to CPUState

Note that target-alpha accesses this field from TCG, now using a
negative offset. Therefore the field is placed last in CPUState.

Pass PowerPCCPU to [kvm]ppc_fixup_cpu() to facilitate this change.

Move common parts of mips cpu_state_reset() to mips_cpu_reset().

Acked-by: Richard Henderson <rth@twiddle.net> (for alpha)
[AF: Rebased onto ppc CPU subclasses and openpic changes]
Signed-off-by: Andreas Färber <afaerber@suse.de>

include/exec/cpu-defs.h

@@ -193,7 +193,6 @@ typedef struct CPUWatchpoint {
     int exception_index;                                                \
                                                                         \
     CPUArchState *next_cpu; /* next CPU sharing TB cache */                 \
-    int cpu_index; /* CPU index (informative) */                        \
     uint32_t host_tid; /* host thread ID */                             \
     int running; /* Nonzero if cpu is currently running(usermode).  */  \
     /* user data */                                                     \

include/exec/gdbstub.h

@@ -35,7 +35,8 @@ static inline int cpu_index(CPUArchState *env)
 #if defined(CONFIG_USER_ONLY) && defined(CONFIG_USE_NPTL)
     return env->host_tid;
 #else
-    return env->cpu_index + 1;
+    CPUState *cpu = ENV_GET_CPU(env);
+    return cpu->cpu_index + 1;
 #endif
 }