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Use a shared array for the duparray instruction

In this example code:

def foo
  [1, 2, 3, 4]
end

The array literal uses a duparray instruction. Before this patch,
rb_ary_resurrect would malloc and memcpy a new array buffer. This
patch changes rb_ary_resurrect to use ary_make_partial so that the
new array object shares the underlying buffer with the array stored in
the instruction sequences.

Before this patch, the new array object is not shared:

$ ruby -r objspace -e'p ObjectSpace.dump([1, 2, 3, 4])'
"{\"address\":\"0x7fa2718372d0\", \"type\":\"ARRAY\", \"class\":\"0x7fa26f8b0010\", \"length\":4, \"memsize\":72, \"flags\":{\"wb_protected\":true}}\n"

After this patch:

$ ./ruby -r objspace -e'p ObjectSpace.dump([1, 2, 3, 4])'
"{\"address\":\"0x7f9a76883638\", \"type\":\"ARRAY\", \"class\":\"0x7f9a758af900\", \"length\":4, \"shared\":true, \"references\":[\"0x7f9a768837c8\"], \"memsize\":40, \"flags\":{\"wb_protected\":true}}\n"

[Feature #15289] [ruby-core:90097]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66095 b2dd03c8-39d4-4d8f-98ff-823fe69b080e