Disable Open MPI's vader byte transfer layer while running tests on 32-bit x86 platforms

to resolve FTBFS issue (BZ#1518038).

fftw.spec

@@ -14,7 +14,7 @@
 
 Name:           fftw
 Version:        3.3.5
-Release:        7%{?dist}
+Release:        8%{?dist}
 Summary:        A Fast Fourier Transform library
 Group:          System Environment/Libraries
 License:        GPLv2+
@@ -407,6 +407,13 @@ do
  make %{?_smp_mflags} -C $ver check
 done
 # MPI
+%if %{with openmpi}
+%ifarch %{ix86}
+# disable Open MPI's vader byte transfer layer while running tests on 32-bit x86 platforms
+# as it is known to be troublesome <https://github.com/open-mpi/ompi/issues/4260>
+export OMPI_MCA_btl="^vader"
+%endif
+%endif
 for mpi in %{mpi_list}
 do
  module load mpi/${mpi}-%{_arch}
@@ -543,6 +550,11 @@ fi
 %endif
 
 %changelog
+* Tue Nov 28 2017 Merlin Mathesius <mmathesi@redhat.com> - 3.3.5-8
+- Disable Open MPI's vader byte transfer layer while running tests on 32-bit x86 platforms
+  as it is known to be troublesome <https://github.com/open-mpi/ompi/issues/4260>.
+  This resolves FTBFS issue (BZ#1518038).
+
 * Wed Aug 02 2017 Fedora Release Engineering <releng@fedoraproject.org> - 3.3.5-7
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_27_Binutils_Mass_Rebuild