support 32-bit and 64-bit binary. Also preserve cf-twin upgrade for 3.5.x clients

(cherry picked from commit ed71b7222e1d086c80c6e93f3c52d5ec1b470741)
Change: Do not define demidecode variables on rhel4

Ref: https://dev.cfengine.com/issues/6302#note-8

For consistency in reporting (and a small decrease in storage space
required) it is better to not define inventory variables that are
unsupported.

(cherry picked from commit cc8c670ece2ef09b7225d27b4f26ce79851d3765)