Revert "Makefile: add lots of compiler optimization flags courtesy of @SaberMod"

This reverts commit d52fc4e1b996086657e1948cf6f9e43867b92c3c.
Revert "Makefile: add arch and cross compile variables"

This reverts commit 88f57ededdb7c74f38ff0ed482a55197328ae1d1.