Build libLLVM.so first to avoid OOM errors

Linking libLLVM.so takes a lot of memory and often causes OOM errors
on builders with low memory:cpu ratios..  By building libLLVM.so first,
we can ensure that when libLLVM.so is being linked, there are no other
build threads running which reduces the chances of an OOM error.

llvm.spec

@@ -14,7 +14,7 @@
 %global min_ver 0
 %global patch_ver 0
 #%%global rc_ver 3
-%global baserelease 2
+%global baserelease 3
 
 
 %if %{with compat_build}
@@ -164,7 +164,7 @@ pathfix.py -i %{__python3} -pn \
 mkdir -p _build
 cd _build
 
-%ifarch s390 s390x %{arm} %ix86
+%ifarch s390 %{arm} %ix86
 # Decrease debuginfo verbosity to reduce memory consumption during final library linking
 %global optflags %(echo %{optflags} | sed 's/-g /-g1 /')
 %endif
@@ -180,7 +180,7 @@ cd _build
 	-DLLVM_PARALLEL_LINK_JOBS=1 \
 	-DCMAKE_BUILD_TYPE=RelWithDebInfo \
 	-DCMAKE_INSTALL_RPATH=";" \
-%ifarch s390 s390x %{arm} %ix86
+%ifarch s390 %{arm} %ix86
 	-DCMAKE_C_FLAGS_RELWITHDEBINFO="%{optflags} -DNDEBUG" \
 	-DCMAKE_CXX_FLAGS_RELWITHDEBINFO="%{optflags} -DNDEBUG" \
 %endif
@@ -239,6 +239,10 @@ cd _build
 	-DLLVM_INSTALL_SPHINX_HTML_DIR=%{_pkgdocdir}/html \
 	-DSPHINX_EXECUTABLE=%{_bindir}/sphinx-build-3
 
+# Build libLLVM.so first.  This ensures that when libLLVM.so is linking, there
+# are no other compile jobs running.  This will help reduce OOM errors on the
+# builders without having to artificially limit the number of concurrent jobs.
+%ninja_build LLVM
 %ninja_build
 
 %install
@@ -476,6 +480,9 @@ fi
 %endif
 
 %changelog
+* Mon Sep 30 2019 Tom Stellard <tstellar@redhat.com> - 9.0.0-3
+- Build libLLVM.so first to avoid OOM errors
+
 * Fri Sep 27 2019 Tom Stellard <tstellar@redhat.com> - 9.0.0-2
 - Remove unneeded BuildRequires: libstdc++-static