Decrease debug info verbosity for some target and prevent parallel linking

clang.spec

@@ -233,12 +233,13 @@ sed -i 's/\@FEDORA_LLVM_LIB_SUFFIX\@//g' test/lit.cfg.py
 mkdir -p _build
 cd _build
 
-%ifarch %{arm}
+%ifarch s390 s390x %{arm} %ix86
 # Decrease debuginfo verbosity to reduce memory consumption during final library linking
 %global optflags %(echo %{optflags} | sed 's/-g /-g1 /')
 %endif
 
 %cmake .. -G Ninja \
+	-DLLVM_PARALLEL_LINK_JOBS=1 \
 	-DLLVM_LINK_LLVM_DYLIB:BOOL=ON \
 	-DCMAKE_BUILD_TYPE=RelWithDebInfo \
 	-DPYTHON_EXECUTABLE=%{__python3} \