GP-3276 Put all C++ classes in ghidra namespace

Ghidra/Features/Decompiler/src/decompile/cpp/flow.cc

@@ -15,6 +15,8 @@
  */
 #include "flow.hh"
 
+namespace ghidra {
+
 /// Prepare for tracing flow for a new function.
 /// The Funcdata object and references to its internal containers must be explicitly given.
 /// \param d is the new function to trace
@@ -1416,3 +1418,4 @@ void FlowInfo::recoverJumpTables(vector<JumpTable *> &newTables,vector<PcodeOp *
   }
 }
 
+} // End namespace ghidra