Reland of land "Turn libbase into a component"

src/base/atomicops_internals_x86_gcc.h

Index: src/base/atomicops_internals_x86_gcc.h
diff --git a/src/base/atomicops_internals_x86_gcc.h b/src/base/atomicops_internals_x86_gcc.h
index 55bc44cd8bd4acd4869d109a4b302f563745d884..8bd0c3bd9e53307b650fbbe6d3cebd43f0c3a6a4 100644
--- a/src/base/atomicops_internals_x86_gcc.h
+++ b/src/base/atomicops_internals_x86_gcc.h
@@ -6,6 +6,8 @@
 
 #ifndef V8_BASE_ATOMICOPS_INTERNALS_X86_GCC_H_
 #define V8_BASE_ATOMICOPS_INTERNALS_X86_GCC_H_
+
+#include "src/base/base-export.h"
 
 namespace v8 {
 namespace base {
@@ -21,7 +23,8 @@
   bool has_sse2;             // Processor has SSE2.
 #endif
 };
-extern struct AtomicOps_x86CPUFeatureStruct AtomicOps_Internalx86CPUFeatures;
+V8_BASE_EXPORT extern struct AtomicOps_x86CPUFeatureStruct
+    AtomicOps_Internalx86CPUFeatures;
 
 #define ATOMICOPS_COMPILER_BARRIER() __asm__ __volatile__("" : : : "memory")