No `-Wdeprecated-declarations` at all on virtual calls

[stbergmann]

Bugzilla Link	19423
Version	trunk
OS	All
CC	@DougGregor

Extended Description

As discussed in the mail thread http://clang-developers.42468.n3.nabble.com/No-Wdeprecated-declarations-at-all-on-virtual-calls-td4038378.html:

The code

  bool ShouldCheckUse = true;
  if (CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(MemberDecl)) {
    // Don't diagnose the use of a virtual member function unless it's
    // explicitly qualified.
    if (MD->isVirtual() && !SS.isSet())
      ShouldCheckUse = false;
  }

in lib/Sema/SemaExprMember.cpp, originally introduced with r81460 to fix http://llvm.org/bugs/show_bug.cgi?id=4878 "ability to call deprecated virtual methods in the same class without warning" prevents warnings on all virtual calls to such deprecated functions. Not just when the call is from the same class, but also when a client of that class calls the function.