Base: Switch base_i18n to be a separate dll (component build)

base/i18n/case_conversion.h

Index: base/i18n/case_conversion.h
===================================================================
--- base/i18n/case_conversion.h	(revision 97736)
+++ base/i18n/case_conversion.h	(working copy)
@@ -6,16 +6,17 @@
 #define BASE_I18N_CASE_CONVERSION_H_
 #pragma once
 
+#include "base/i18n/base_i18n_export.h"
 #include "base/string_piece.h"
 
 namespace base {
 namespace i18n {
 
 // Returns the lower case equivalent of string. Uses ICU's default locale.
-string16 ToLower(const StringPiece16& string);
+BASE_I18N_EXPORT string16 ToLower(const StringPiece16& string);
 
 // Returns the upper case equivalent of string. Uses ICU's default locale.
-string16 ToUpper(const StringPiece16& string);
+BASE_I18N_EXPORT string16 ToUpper(const StringPiece16& string);
 
 }  // namespace i18n
 }  // namespace base