Revert r168519, "Merge used flags so that we don't have to iterate on isUsed. With...

Revert r168519, "Merge used flags so that we don't have to iterate on isUsed. With this change"

It brought bunch of (possibly false) warnings.

llvm/unittests/VMCore/PassManagerTest.cpp:60:22: warning: variable 'ID' is not needed and will not be emitted [-Wunneeded-internal-declaration]
    char ModuleNDNM::ID=0;
                     ^
llvm/unittests/VMCore/PassManagerTest.cpp:86:22: warning: variable 'ID' is not needed and will not be emitted [-Wunneeded-internal-declaration]
    char ModuleNDM2::ID=0;
                     ^
llvm/unittests/VMCore/PassManagerTest.cpp:106:21: warning: variable 'ID' is not needed and will not be emitted [-Wunneeded-internal-declaration]
    char ModuleDNM::ID=0;
                    ^
llvm/unittests/VMCore/PassManagerTest.cpp:217:16: warning: variable 'initcount' is not needed and will not be emitted [-Wunneeded-internal-declaration]
    int LPass::initcount=0;
               ^
llvm/unittests/VMCore/PassManagerTest.cpp:218:16: warning: variable 'fincount' is not needed and will not be emitted [-Wunneeded-internal-declaration]
    int LPass::fincount=0;
               ^
llvm/unittests/VMCore/PassManagerTest.cpp:259:16: warning: variable 'inited' is not needed and will not be emitted [-Wunneeded-internal-declaration]
    int BPass::inited=0;
               ^
llvm/unittests/VMCore/PassManagerTest.cpp:260:16: warning: variable 'fin' is not needed and will not be emitted [-Wunneeded-internal-declaration]
    int BPass::fin=0;
               ^
llvm/unittests/VMCore/PassManagerTest.cpp:283:24: warning: variable 'ID' is not needed and will not be emitted [-Wunneeded-internal-declaration]
    char OnTheFlyTest::ID=0;
                       ^
8 warnings generated.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@168549 91177308-0d34-0410-b5e6-96231b3b80d8