Move OS::MemCopy and OS::MemMove out of platform to utils

src/debug.cc

Index: src/debug.cc
diff --git a/src/debug.cc b/src/debug.cc
index b4421d6df8f2ffa51ce10a8f35d7b955bf4b3a99..53fc57a2cae89a68357738cf22ffbd13e9b3909e 100644
--- a/src/debug.cc
+++ b/src/debug.cc
@@ -515,7 +515,7 @@ void Debug::ThreadInit() {
 
 char* Debug::ArchiveDebug(char* storage) {
   char* to = storage;
-  OS::MemCopy(to, reinterpret_cast<char*>(&thread_local_), sizeof(ThreadLocal));
+  MemCopy(to, reinterpret_cast<char*>(&thread_local_), sizeof(ThreadLocal));
   ThreadInit();
   return storage + ArchiveSpacePerThread();
 }
@@ -523,8 +523,7 @@ char* Debug::ArchiveDebug(char* storage) {
 
 char* Debug::RestoreDebug(char* storage) {
   char* from = storage;
-  OS::MemCopy(
-      reinterpret_cast<char*>(&thread_local_), from, sizeof(ThreadLocal));
+  MemCopy(reinterpret_cast<char*>(&thread_local_), from, sizeof(ThreadLocal));
   return storage + ArchiveSpacePerThread();
 }