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

src/arm/assembler-arm.cc

Index: src/arm/assembler-arm.cc
diff --git a/src/arm/assembler-arm.cc b/src/arm/assembler-arm.cc
index 8465d22066b355fc0005f820c7c349eac5691946..46712d5e17db36548e05fb87fa1fc6741e0b8aab 100644
--- a/src/arm/assembler-arm.cc
+++ b/src/arm/assembler-arm.cc
@@ -2325,7 +2325,7 @@ void  Assembler::vstm(BlockAddrMode am,
 
 static void DoubleAsTwoUInt32(double d, uint32_t* lo, uint32_t* hi) {
   uint64_t i;
-  OS::MemCopy(&i, &d, 8);
+  MemCopy(&i, &d, 8);
 
   *lo = i & 0xffffffff;
   *hi = i >> 32;
@@ -3114,9 +3114,9 @@ void Assembler::GrowBuffer() {
   // Copy the data.
   int pc_delta = desc.buffer - buffer_;
   int rc_delta = (desc.buffer + desc.buffer_size) - (buffer_ + buffer_size_);
-  OS::MemMove(desc.buffer, buffer_, desc.instr_size);
-  OS::MemMove(reloc_info_writer.pos() + rc_delta,
-              reloc_info_writer.pos(), desc.reloc_size);
+  MemMove(desc.buffer, buffer_, desc.instr_size);
+  MemMove(reloc_info_writer.pos() + rc_delta, reloc_info_writer.pos(),
+          desc.reloc_size);
 
   // Switch buffers.
   DeleteArray(buffer_);