The current compile tools require certain CPU extensions in order to work, meaning they'll just fail on older systems even if the actual builds they produce work fine. There is nothing you can do to fix that. (the tools were upgraded because compiling with older ones was causing bugs in some drivers)
I think it is a design choice from the guys who make the toolchain, unless they simply enabled some optimization by mistake, but that seems unlikely. This is beyond the control of Mamedev, we simply use what is available.
Due to the nature of your request I'll be providing no further help, and remind people that distributing any builds with such mods, to anybody, is seriously frowned upon.