S390: Guard auvx.h include with V8_HOST_ARCH_S390

The s390 port uses the auxvector APIs to detect hardware/OS
support for various z/Architecture features.  These checks
only make sense if we are running native, non-simulator mode.

Moving the include<auxv.h> under V8_HOST_ARCH_S390 enables
compilation of s390 simulation on platforms that do not have auxv.h
header available.

R=miladfar@ca.ibm.com,jyan@ca.ibm.com

Change-Id: I685681a4f8786509beb181d8ae63876b3a4235b2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1726844Reviewed-by: Milad Farazmand <miladfar@ca.ibm.com>
Commit-Queue: Joran Siu <joransiu@ca.ibm.com>
Cr-Commit-Position: refs/heads/master@{#62999}

src/codegen/s390/assembler-s390.cc

@@ -35,7 +35,6 @@
 // Copyright 2014 the V8 project authors. All rights reserved.
 
 #include "src/codegen/s390/assembler-s390.h"
-#include <sys/auxv.h>
 #include <set>
 #include <string>
 
@@ -43,6 +42,7 @@
 
 #if V8_HOST_ARCH_S390
 #include <elf.h>  // Required for auxv checks for STFLE support
+#include <sys/auxv.h>
 #endif
 
 #include "src/base/bits.h"