Remove assert in sse_round_fn and handle case where src2 is in memory

[sydhds]

In Singlepass SSE4.2 backend and for sse_round_fn function, some special cases were not handled:

• src1 != src2
• src2 is in memory

This should fix those cases.

This is a follow up of ticket #3461

[ptitSeb]

Please create a if / else branch

[ptitSeb]

So, I reviewed the ROUNDSS/VROUNDSS opcode (for example, it's one of the opcode use here): https://www.felixcloutier.com/x86/roundss
And it's not what I imagined.
So the code should be:

if x != dst {
 move_src_to_dst(emitter, precision, src1, dst);
}
dynasm!(emitter ; $ins Rx((x as u8)), Rx((dst as u8)), $mode)

Basicaly a bigger change, but that version should be exact. It's not important for now, as ROUND functions are basically used as 2 operators opcode, never as 3-way in Singlepass.

[syrusakbary]

It should already be approved. But approving again to see if that trigger tests

[syrusakbary]

Merged manually, as I had no idea why tests are not being executed (we will revert in case tests fail)

[theduke]

@syrusakbary Github Actions have been problematic the last two days, also on other repos.
Timeouts, network errors, jobs just sitting idle forever, ...