[Bug target/88451] No rounding in fixed-point arithmetic (Decimal to fixed-point conversion, multiplication)

[mantas.mikaitis at manchester dot ac.uk]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88451

--- Comment #2 from Mantas Mikaitis <mantas.mikaitis at manchester dot ac.uk> 
---
Created attachment 45212
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=45212&action=edit
3 simple testcases