[Fedora-packaging] Use of %__isa_bits should be mandatory

[Marcin Juszkiewicz]

Hi

I am working on porting Fedora for AArch64 architecture. This means
patching many packages and during that time I noticed lot of checks for
32/64-bit architectures.

Most common one is:

%global something 32
%ifarch x86_64 ppc64 s390
%global something 64
%endif

Which can be now replaced to simple:

%global something %{__isa_bits}

And this works fine in Fedora 19 and beyond (including RHEL 7). There
are also some other variations of 32/64-bit checks which could be converted.

Can use of %__isa_bits be somehow announced/suggested to developers?
Would cut amount of patching needed for each new architecture.