Integer legalization: fix MUL expansion
Summary:
This fixes the runtime results produces by the fallback multiplication expansion introduced in r270720.
For tests I created a fuzz tester that compares the results with Boost.Multiprecision.
Reviewers: hfinkel
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D26628
llvm-svn: 286998