Use ExclusiveArch: %{kernel_arches}

kernel_arches is a new rpm macro variable that is now in the Fedora buildroot as of redhat-rpm-config-167.
It lists what architectures the full kernel is built on.
Architectures that only have the kernel-header (such as i686) is not listed.
Thus, it can be used as a variable so that packages that depend on the kernel, can have a consistent way of listing the architectures.
The variable is currently only in Fedora, but is expected to be in RHEL9, and hopefully backported to earlier RHEL versions.

This pull request updates the spec to use %{kernel_arches} for ExclusiveArch:

supermin.spec

@@ -29,14 +29,10 @@
 Summary:       Tool for creating supermin appliances
 Name:          supermin
 Version:       5.2.0
-Release:       3%{?dist}
+Release:       4%{?dist}
 License:       GPLv2+
 
-%if 0%{?rhel} >= 7
-ExclusiveArch: x86_64
-%endif
-
-ExcludeArch:   %{ix86}
+ExclusiveArch: %{kernel_arches}
 
 URL:           http://people.redhat.com/~rjones/supermin/
 Source0:       http://download.libguestfs.org/supermin/%{source_directory}/%{name}-%{version}.tar.gz
@@ -168,6 +164,9 @@ make check || {
 
 
 %changelog
+* Fri Aug 07 2020 Troy Dawson <tdawson@redhat.com> - 5.2.0-4
+- Use ExclusiveArch: %{kernel_arches}
+
 * Wed Jul 29 2020 Fedora Release Engineering <releng@fedoraproject.org> - 5.2.0-3
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_33_Mass_Rebuild