[ELF] Move InputSectionBase::rawData member [NFC]

lld/ELF/InputSection.h

@@ -149,6 +149,8 @@ public:
     bytesDropped -= num;
   }
 
+  mutable ArrayRef<uint8_t> rawData;
+
   void trim() {
     if (bytesDropped) {
       rawData = rawData.drop_back(bytesDropped);
@@ -220,8 +222,6 @@ public:
     return llvm::makeArrayRef<T>((const T *)rawData.data(), s / sizeof(T));
   }
 
-  mutable ArrayRef<uint8_t> rawData;
-
 protected:
   template <typename ELFT>
   void parseCompressedHeader();