Architecture specific change in rpms/pynac.git

The package rpms/pynac.git has added or updated architecture specific content in its
spec file (ExclusiveArch/ExcludeArch or %ifarch/%ifnarch) in commit(s):
https://src.fedoraproject.org/cgit/rpms/pynac.git/commit/?id=c8c7fb838d0ed30....

Change:
+%ifnarch aarch64 %{power64} s390x

Thanks.

Full change:
============

commit c8c7fb838d0ed30d41f738c849a5ffad9340c890
Author: Jerry James 
Date:   Sat Sep 30 20:39:30 2017 -0600

Only BR giac-devel on supported architectures

diff --git a/pynac.spec b/pynac.spec
index ddc6db3..6e2c050 100644
--- a/pynac.spec
+++ b/pynac.spec
@@ -9,10 +9,13 @@ Source0:        http://www.sagemath.org/packages/upstream/pynac/%%7Bname%7D-%%7Bversio

BuildRequires:  factory-devel
 BuildRequires:  flint-devel
-BuildRequires:  giac-devel
 BuildRequires:  gmp-devel
 BuildRequires:  python2-devel

+%ifnarch aarch64 %{power64} s390x
+BuildRequires:  giac-devel
+%endif
+

%description
 Pynac is a derivative of the C++ library GiNaC, which allows manipulation of
@@ -69,7 +72,7 @@ rm -f %{buildroot}%{_libdir}/*.la

%changelog
 * Sat Sep 30 2017 Jerry James  - 0.7.5-4
-- Build with giac support
+- Build with giac support on supported architectures
 - Add --disable-silent-rules to configure invocation
 - Explicitly use python 2 until we are ready to switch to python 3