jenkins: Disable parallel make as it is broken right now

sed -i 's,^#include "ranap_ies_defs.h",#include <osmocom/ranap/ranap_ies_defs.h>,' ranap_encoder.c ranap_decoder.c
sed -i 's,^#include "ranap_common.h",#include <osmocom/ranap/ranap_common.h>,' ranap_encoder.c ranap_decoder.c ranap_ies_defs.h
sed -i 's,^#include "ranap_common.h",#include <osmocom/ranap/ranap_common.h>,' ranap_encoder.c ranap_decoder.c ranap_ies_defs.h
mv ranap_ies_defs.h ../include/osmocom/ranap/
sed: can't read ranap_ies_defs.h: No such file or directory
Makefile:916: recipe for target 'ranap_decoder.c' failed
1 file changed