This mode has been broken for a long time because it's mostly untested.
Barriers, and backpatching while slow have proven that they work.
Maintain the one TSO path, at least until all ARM hardware gains support for
x86-TSO memory model mode.
This adds a new mode X87StrictReducedPrecision.
The strict reduced precision is like the reduced precision but adds extra checks,
like the currently implemented nan and snan propagations.
Fix for __builtin_issignaling() test of SPEC2017 classify test.