Reland "Turn libbase into a component"

src/base/once.h

Index: src/base/once.h
diff --git a/src/base/once.h b/src/base/once.h
index 790a8866e09bf682eba6eff4f2016cafcca8469c..8008812d75814e60e1687ab512dff687a1f68106 100644
--- a/src/base/once.h
+++ b/src/base/once.h
@@ -55,6 +55,7 @@
 #include <stddef.h>
 
 #include "src/base/atomicops.h"
+#include "src/base/base-export.h"
 
 namespace v8 {
 namespace base {
@@ -79,7 +80,8 @@ struct OneArgFunction {
   typedef void (*type)(T);
 };
 
-void CallOnceImpl(OnceType* once, PointerArgFunction init_func, void* arg);
+V8_BASE_EXPORT void CallOnceImpl(OnceType* once, PointerArgFunction init_func,
+                                 void* arg);
 
 inline void CallOnce(OnceType* once, NoArgFunction init_func) {
   if (Acquire_Load(once) != ONCE_STATE_DONE) {