ChangeList: The CauseWay DOS extender now installs its own protected-mode
IRQ 13 (INT 75h) handler to ensure that floating-point exceptions are
handled consistently.

Note: This change brings CW in line with DOS/4G(W). When a protected-mode IRQ 13
handler wasn't installed, in some environments (plain DOS, OS/2 DOS box, but not
NTVDM) FPEs never reached the handler installed by the clib, either the default
one or a user-provided handler. Problem clearly visible in mathlib qa test.

[git-p4: depot-paths = "//depot/openwatcom/": change = 37559]

(cherry picked from commit 033bc8ff680f217818b571343575df36bdd1562e)