Use address-taken to disambiguate global variable and indirect memops.

Major steps include:
 1). introduces a not-addr-taken bit-field in GlobalVariable
 2). GlobalOpt pass sets "not-address-taken" if it proves a global varirable 
    dosen't have its address taken.
 3). AA use this info for disambiguation. 


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193251 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/IPO/GlobalOpt.cpp

@@ -1723,6 +1723,7 @@ bool GlobalOpt::ProcessGlobal(GlobalVariable *GV,
   if (GlobalStatus::analyzeGlobal(GV, GS))
     return false;
 
+  GV->setAddressMaybeTaken(false);
   if (!GS.IsCompared && !GV->hasUnnamedAddr()) {
     GV->setUnnamedAddr(true);
     NumUnnamed++;