rgw_crypt: make decrypt's parts_len protected

This is so that testing classes can set this and use that to test the branches
in fixup_range tests

Signed-off-by: Abhishek Lekshmanan <abhishek@suse.com>
(cherry picked from commit 78b37a5)

src/rgw/rgw_crypt.h

@@ -93,9 +93,11 @@ class RGWGetObj_BlockDecrypt : public RGWGetObj_Filter {
   off_t end; /**< stream offset of last byte that is requested */
   bufferlist cache; /**< stores extra data that could not (yet) be processed by BlockCrypt */
   size_t block_size; /**< snapshot of \ref BlockCrypt.get_block_size() */
-  std::vector<size_t> parts_len; /**< size of parts of multipart object, parsed from manifest */
 
   int process(bufferlist& cipher, size_t part_ofs, size_t size);
+
+protected:
+  std::vector<size_t> parts_len; /**< size of parts of multipart object, parsed from manifest */
 public:
   RGWGetObj_BlockDecrypt(CephContext* cct,
                          RGWGetDataCB* next,