Fix UseAuto replacing variable declaration lists containing non-initialized
variables.

UseAuto used to match initialized variable declarations independently of
whether they were defined in a declaration list or as a single declaration.
Now it matches declaration statements where every variable declaration is
initialized.


git-svn-id: https://llvm.org/svn/llvm-project/clang-tools-extra/trunk@182114 91177308-0d34-0410-b5e6-96231b3b80d8