llvm-link: Verify input modules

llvm-link: Verify input modules

Otherwise, broken input modules can cause assertions.  I've updated two
of the testcases that started failing (modules that had `Require` flags
but didn't meet their own requirements), but Rafael and I decided that
test/Linker/2011-08-22-ResolveAlias.ll should just be deleted outright
-- it's a leftover of the way llvm-gcc used to implement weakref.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233229 91177308-0d34-0410-b5e6-96231b3b80d8