Why 3 variants of this?  The X86-64 one doesn't match one of the values you've filtered on so should probably be removed.

It may make more sense to abstract this further anyway so that we provide a variable for ARCH_WORD_SIZE or something and make it 32/64.  The main advantage of doing system identification in one place is to simplify/abstract the details away from the rest of the makefiles.  That means just not setting any of these 3 things but rather a single ````ARCH_WORD_SIZE :=64````.