cpu: add CPU_RESOLVING_TYPE macro

it will be used for providing to cpu name resolving class for
parsing cpu model for system and user emulation code.

Along with change add target to null-machine tests, so
that when switch to CPU_RESOLVING_TYPE happens,
it would ensure that null-machine usecase still works.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu> (m68k)
Acked-by: David Gibson <david@gibson.dropbear.id.au> (ppc)
Acked-by: Bastian Koppelmann <kbastian@mail.uni-paderborn.de> (tricore)
Message-Id: <1518000027-274608-4-git-send-email-imammedo@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
[ehabkost: Added macro to riscv too]
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index 1e7e1f8..f4b4258 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -2306,6 +2306,7 @@
 
 #define ARM_CPU_TYPE_SUFFIX "-" TYPE_ARM_CPU
 #define ARM_CPU_TYPE_NAME(name) (name ARM_CPU_TYPE_SUFFIX)
+#define CPU_RESOLVING_TYPE TYPE_ARM_CPU
 
 #define cpu_signal_handler cpu_arm_signal_handler
 #define cpu_list arm_cpu_list