Try the experiment:
1) Check the shell: echo $SHELL. (I expect bash.)
2) check the variable: set | grep MACHTYPE(I expect "x86_64-pc-linux-gnu".)
3) : printenv | grep MACHTYPE ( , .)
4) makefile $(info MACHTYPE is $(MACHTYPE)) make. ( , "MACHTYPE is", .)
5) make MACHTYPE=$MACHTYPE.
EDIT:
! , MACHTYPE ( make), ( ). , Make , make MACHTYPE=$MACHTYPE MACHTYPE :
export MACHTYPE
make
( .)