still doesn't work with vscode

Let's see if bots happy.

Not sure where else we can use these.  Mm.  Maybe in hb_invoke().

Has not been updated.

This reverts commit 694cb1be.

To fix bogus MSVC warnings:

  c:\projects\harfbuzz\src\hb-array.hh(189): warning C4521: 'hb_array_t<Type>': multiple copy constructors specified [C:\projects\harfbuzz\build\harfbuzz.vcxproj]
  c:\projects\harfbuzz\src\hb-array.hh(189): warning C4522: 'hb_array_t<Type>': multiple assignment operators specified [C:\projects\harfbuzz\build\harfbuzz.vcxproj]

If they're not, it's a bug in our subsetting logic somewhere.  So check.

Calls obj.copy() or obj.operator=() in that order.