Do not build in parallel since the Makefile does not support it.

ocaml-sedlex.spec

@@ -1,6 +1,6 @@
 Name:           ocaml-sedlex
 Version:        1.99.4
-Release:        4%{?dist}
+Release:        5%{?dist}
 Summary:        Unicode-friendly lexer generator
 
 License:        MIT
@@ -42,10 +42,10 @@ files for developing applications that use %{name}.
 chmod a-x src/syntax/sedlex_cset.ml
 
 %build
-%make_build
+make
 
 %ifarch %{ocaml_native_compiler}
-%make_build opt
+make opt
 %endif
 
 %install
@@ -86,6 +86,9 @@ find $RPM_BUILD_ROOT -name '*.{cmxs,opt}' -exec chmod 0755 {} \;
 
 
 %changelog
+* Thu Feb 14 2019 Andy Li <andy@onthewings.net> - 1.99.4-5
+- Do not build in parallel since the Makefile does not support it.
+
 * Fri Feb 01 2019 Fedora Release Engineering <releng@fedoraproject.org> - 1.99.4-4
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_30_Mass_Rebuild