[WebAssembly] Don't include lazy symbols in import table

This bug was introduced in: https://reviews.llvm.org/D41304.
Add a test for this case.

Differential Revision: https://reviews.llvm.org/D41309

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@320872 91177308-0d34-0410-b5e6-96231b3b80d8