Index: VirtualBox-5.1.8/src/libs/libxml2-2.9.2/libxml.spec.in
===================================================================
--- VirtualBox-5.1.8.orig/src/libs/libxml2-2.9.2/libxml.spec.in
+++ VirtualBox-5.1.8/src/libs/libxml2-2.9.2/libxml.spec.in
@@ -69,7 +69,7 @@ at parse time or later once the document
 
 %build
 %configure
-make %{_smp_mflags}
+make 
 
 %install
 rm -fr %{buildroot}
Index: VirtualBox-5.1.8/src/libs/libxml2-2.9.2/libxml2.spec
===================================================================
--- VirtualBox-5.1.8.orig/src/libs/libxml2-2.9.2/libxml2.spec
+++ VirtualBox-5.1.8/src/libs/libxml2-2.9.2/libxml2.spec
@@ -69,7 +69,7 @@ at parse time or later once the document
 
 %build
 %configure
-make %{_smp_mflags}
+make 
 
 %install
 rm -fr %{buildroot}