When checking for weak vtables, check whether the actual definition of

When checking for weak vtables, check whether the actual definition of
the key function is inline, rather than the original
declaration. Perhaps FunctionDecl::isInlined() is poorly named. Fixes
<rdar://problem/9979458>.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@140400 91177308-0d34-0410-b5e6-96231b3b80d8