Fix conditional setting of build tools variables in the makefile As pointed out by Tormod Volden, make automatically sets CC and AR. Instead of a conditional setting of those variables, automatically add BUILDTPREFIX to them if it is set without overriding the values of CC, AR, and RANLIB. Also have extra default conditional settings of those three variables in the event that they happen not to be set for some reason.

\.exe$
\.o$
\.d$
\.a$
~$
\.orig$
/lwbasic$
/lwlink$
/lwobjdump$
/lwar$
/lwasm$
/lwcc/lwcc$
/lwcc/lwcpp$