HostFeatures: Supports runtime disabling of preserve_all

This is used for instcountci to ensure instruction counts don't change
when a compiler supports this feature or not. Always runtime disable
when running in instcountci.

CMake option from #3394 can still be useful so leaving that in place.

Source/Tools/CodeSizeValidation/Main.cpp

@@ -549,6 +549,9 @@ int main(int argc, char **argv, char **const envp) {
     HostFeatureControl |= static_cast<uint64_t>(FEXCore::Config::HostFeatures::DISABLECRYPTO);
   }
 
+  // Always disable preserve_all abi.
+  HostFeatureControl |= static_cast<uint64_t>(FEXCore::Config::HostFeatures::DISABLEPRESERVEALLABI);
+
   FEXCore::Config::EraseSet(FEXCore::Config::CONFIG_HOSTFEATURES, fextl::fmt::format("{}", HostFeatureControl));
   FEXCore::Config::EraseSet(FEXCore::Config::CONFIG_FORCESVEWIDTH, fextl::fmt::format("{}", SVEWidth));