testnode: Build NumPy/friends & Ruby gems in parallel

Following @rafael advice on a related commit to slaprunner

    nexedi/slapos@c8c81baa
    nexedi/slapos!22 (comment 1780)

let's also leverage multicore when building NumPy- & Ruby- related
software under testnodes.

/reviewed-by @rafael, @seb  (on !23)

erp5/util/testnode/SlapOSControler.py

@@ -336,6 +336,8 @@ class SlapOSControler(object):
     self.log("SlapOSControler.runSoftwareRelease")
     cpu_count = os.sysconf("SC_NPROCESSORS_ONLN")
     os.putenv('MAKEFLAGS', '-j%s' % cpu_count)
+    os.putenv('NPY_NUM_BUILD_JOBS', '%s' % cpu_count)
+    os.putenv('BUNDLE_JOBS', '%s' % cpu_count)
     os.environ['PATH'] = environment['PATH']
     # a SR may fail for number of reasons (incl. network failures)
     # so be tolerant and run it a few times before giving up