Add CalculateSymbolSizes in ObjectFilePECOFF::GetSymtab to ensure that (nearly) all the symbols have sizes.

This fixes the `thread step-over` regression exposed by http://reviews.llvm.org/D16186 , which depends on the symbols having actual sizes.  Nine tests on Windows had started failing as a result.  They all work again with this fix.

Differential Revision: http://reviews.llvm.org/D16415

llvm-svn: 258429

lldb/source/Plugins/ObjectFile/PECOFF/ObjectFilePECOFF.cpp

@@ -649,6 +649,7 @@ ObjectFilePECOFF::GetSymtab()
                     symbols[i].SetDebug(true);
                 }
             }
+            m_symtab_ap->CalculateSymbolSizes();
         }
     }
     return m_symtab_ap.get();