Add suffix parameter to DumpCFG

In a lot of cases it is practical to dump CFGs. However the current dumper
has a unique naming convention. By adding an optional suffix, we can dump
the same CompilationUnit before and after an optimization by using a different
suffix.

Also, by making it optional, the change is minimal.

Change-Id: Ibd7f217ed59c093580cad9c177f9fc174a0afc11
Signed-off-by: Jean Christophe Beyler <jean.christophe.beyler@intel.com>
diff --git a/compiler/dex/mir_graph.h b/compiler/dex/mir_graph.h
index a80c32d..010de20 100644
--- a/compiler/dex/mir_graph.h
+++ b/compiler/dex/mir_graph.h
@@ -452,7 +452,13 @@
     return m_units_[current_method_];
   }
 
-  void DumpCFG(const char* dir_prefix, bool all_blocks);
+  /**
+   * @brief Dump a CFG into a dot file format.
+   * @param dir_prefix the directory the file will be created in.
+   * @param all_blocks does the dumper use all the basic blocks or use the reachable blocks.
+   * @param suffix does the filename require a suffix or not (default = nullptr).
+   */
+  void DumpCFG(const char* dir_prefix, bool all_blocks, const char* suffix = nullptr);
 
   void InitRegLocations();