[ConfigParser] Don't warn about deprecated configparser.hh when compiling

configparser.cc.

Rationale: don't spam the user with warnings he can do nothing about.  He will
still get warnings when he uses the ConfigParser in is his own programs, and
we (as developers) will have to remove configparser.cc the same instant we
remove configparser.hh anyway.

[[Imported from SVN: r6356]]

dune/common/configparser.cc

@@ -5,6 +5,8 @@
 #include "config.h"
 #endif
 
+#define SILENCE_CONFIGPARSER_HH_DEPRECATION
+
 #include "configparser.hh"
 
 #include <cstdlib>

dune/common/configparser.hh

@@ -3,10 +3,12 @@
 #ifndef DUNE_CONFIGPARSER_HH
 #define DUNE_CONFIGPARSER_HH
 
+#ifndef SILENCE_CONFIGPARSER_HH_DEPRECATION
 #warning This file has been deprecated in dune-common 2.1, and will most likely\
   be removed in dune-common 2.2.  In its place, use parametertree.hh to keep\
   hierarchical string-based data, and parametertreeparser.hh to read such data\
   from files and streams.
+#endif // !SILENCE_CONFIGPARSER_HH_DEPRECATION
 
 #include <iostream>
 #include <istream>