Move platform abstraction to base library

src/arm64/assembler-arm64-inl.h

Index: src/arm64/assembler-arm64-inl.h
diff --git a/src/arm64/assembler-arm64-inl.h b/src/arm64/assembler-arm64-inl.h
index 135858d8b1c1d9c43ee281c5a00b1c1bbb39efdf..444f2c4a9455316605d00da9d61a8f2f86ef2fca 100644
--- a/src/arm64/assembler-arm64-inl.h
+++ b/src/arm64/assembler-arm64-inl.h
@@ -6,7 +6,7 @@
 #define V8_ARM64_ASSEMBLER_ARM64_INL_H_
 
 #include "src/arm64/assembler-arm64.h"
-#include "src/cpu.h"
+#include "src/assembler.h"
 #include "src/debug.h"
 
 
@@ -652,7 +652,7 @@ void Assembler::set_target_address_at(Address pc,
   Memory::Address_at(target_pointer_address_at(pc)) = target;
   // Intuitively, we would think it is necessary to always flush the
   // instruction cache after patching a target address in the code as follows:
-  //   CPU::FlushICache(pc, sizeof(target));
+  //   CpuFeatures::FlushICache(pc, sizeof(target));
   // However, on ARM, an instruction is actually patched in the case of
   // embedded constants of the form:
   // ldr   ip, [pc, #...]