[in dev] building msr multiplexing functions

sched_credit.c : bug fix caused by bad version of previously modified sched_credit.c that belonged to xen 4.3.0 version
		 changes to be compatible with kernel.c

kernel.c : small changes to be compatible with sched_credit.c

Makefile : small changes to be less convenient for me
	   multithread compilation option to be fully optimized (number of cores *2)