cpu-exec: Purge all uses of ENV_GET_CPU()

Remove un-needed usages of ENV_GET_CPU() by converting the APIs to use
CPUState pointers and retrieving the env_ptr as minimally needed.

Scripted conversion for target-* change:

for I in target-*/cpu.h; do
    sed -i \
    's/\(^int cpu_[^_]*_exec(\)[^ ][^ ]* \*s);$/\1CPUState *cpu);/' \
    $I;
done

Signed-off-by: Peter Crosthwaite <crosthwaite.peter@gmail.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
diff --git a/target-xtensa/cpu.h b/target-xtensa/cpu.h
index b89c602..96bfc82 100644
--- a/target-xtensa/cpu.h
+++ b/target-xtensa/cpu.h
@@ -399,7 +399,7 @@
 
 void xtensa_translate_init(void);
 void xtensa_breakpoint_handler(CPUState *cs);
-int cpu_xtensa_exec(CPUXtensaState *s);
+int cpu_xtensa_exec(CPUState *cpu);
 void xtensa_finalize_config(XtensaConfig *config);
 void xtensa_register_core(XtensaConfigList *node);
 void check_interrupts(CPUXtensaState *s);