cpu: Add Error argument to cpu_exec_init()

Add an Error argument to cpu_exec_init() to let users collect the
error. This is in preparation to change the CPU enumeration logic
in cpu_exec_init(). With the new enumeration logic, cpu_exec_init()
can fail if cpu_index values corresponding to max_cpus have already
been handed out.

Since all current callers of cpu_exec_init() are from instance_init,
use error_abort Error argument to abort in case of an error.

Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Peter Crosthwaite <crosthwaite.peter@gmail.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>

target-lm32/cpu.c

@@ -151,7 +151,7 @@ static void lm32_cpu_initfn(Object *obj)
     static bool tcg_initialized;
 
     cs->env_ptr = env;
-    cpu_exec_init(env);
+    cpu_exec_init(env, &error_abort);
 
     env->flags = 0;