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