Reland of land "Turn libbase into a component"

src/base/sys-info.h

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_BASE_SYS_INFO_H_
 #define V8_BASE_SYS_INFO_H_
 
 #include <stdint.h>
+
+#include "src/base/base-export.h"
 #include "src/base/compiler-specific.h"
 
 namespace v8 {
 namespace base {
 
-class SysInfo final {
+class V8_BASE_EXPORT SysInfo final {
  public:
   // Returns the number of logical processors/core on the current machine.
   static int NumberOfProcessors();
 
   // Returns the number of bytes of physical memory on the current machine.
   static int64_t AmountOfPhysicalMemory();
 
   // Returns the number of bytes of virtual memory of this process. A return
   // value of zero means that there is no limit on the available virtual memory.
   static int64_t AmountOfVirtualMemory();
 };
 
 }  // namespace base
 }  // namespace v8
 
 #endif  // V8_BASE_SYS_INFO_H_