Added unit tests for the does_remove_const class

Author: thk123

src/analyses/does_remove_const.h

@@ -12,6 +12,7 @@
 #define CPROVER_ANALYSES_DOES_REMOVE_CONST_H
 
 #include <util/type.h>
+#include <util/namespace.h>
 
 class goto_programt;
 
@@ -29,6 +30,8 @@ class does_remove_constt
 
   const goto_programt &goto_program;
   const namespacet &ns;
+
+  friend class does_remove_const_testt;
 };
 
 #endif // CPROVER_ANALYSES_DOES_REMOVE_CONST_H

unit/Makefile

@@ -1,6 +1,7 @@
 .PHONY: all cprover.dir test
 
 SRC = unit_tests.cpp \
+      analyses/does_remove_const/does_expr_lose_const.cpp \
       catch_example.cpp \
       # Empty last line