architecture: remove support for DEC Alpha CPUs

This architecture can be considered pretty dead

https://en.wikipedia.org/wiki/DEC_Alpha
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On June 25, 2001, Compaq announced that Alpha would be phased out by 2004 in
favor of Intel's Itanium, canceled the planned EV8 chip, and sold all Alpha
intellectual property to Intel.
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architecture: added generic arm config options

Note:

This options are available when "generic" optimization is selected!