THRIFT-2835 Add possibility to distribute generators separately from thrift core, and load them dynamically
Client: Compiler
Patch: Nobuaki Sukegawa, rebased by dtmuller

Also fixed by dtmuller:
* Add plugin namespace for erlang language binding
* Fix unit test test_const_value
* Don't clear type cache with every t_program conversion
* Type "wb" may not be supported by popen on non-Windows platforms
* Fix constness of AST type signatures
diff --git a/compiler/cpp/src/logging.h b/compiler/cpp/src/logging.h
index 3f1fce8..ebefbf2 100644
--- a/compiler/cpp/src/logging.h
+++ b/compiler/cpp/src/logging.h
@@ -20,7 +20,9 @@
 #ifndef T_LOGGING_H
 #define T_LOGGING_H
 
-#include <string>
+extern int g_debug;
+extern int g_warn;
+extern int g_verbose;
 
 /**
  * Parse debugging output, used to print helpful info