consider using arch-bits=32/64 syntax if possible?

[YunQiang Su]

I am working to port Debian to some new architectures, and some packages ftbfs
due to symbol file error, and most of them is due to difference
between 32bit and 64bit.

I noticed that in dpkg 1.18.0, dpkg-gensymbols has support a new syntax,
    (arch-bits=32)32bit_specific_symbol@Base 1.0
    (arch-bits=64)64bit_specific_symbol@Base 1.0

Since stretch's dpkg is greater than 1.18.0, backport won't be a quite
big block.
Should we ask for all packages use this new syntax if possible?

-- 
YunQiang Su