[DAGCombiner] Do not generate ISD::ADDE node if adde is not legal for the target...

[DAGCombiner] Do not generate ISD::ADDE node if adde is not legal for the target when combine ISD::TRUNC node

Do not combine (trunc adde(X, Y, Carry)) into (adde trunc(X), trunc(Y), Carry),
if adde is not legal for the target. Even it's at type-legalize phase.
Because adde is special and will not be legalized at operation-legalize phase later.

This fixes: PR40922
https://bugs.llvm.org/show_bug.cgi?id=40922

Differential Revision: https://reviews.llvm.org//D60854

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@359532 91177308-0d34-0410-b5e6-96231b3b80d8