implement get_coverage method

Signed-off-by: Lucas Cordeiro <[email protected]>

Author: lucasccordeiro

src/goto-instrument/cover.cpp

@@ -22,6 +22,8 @@ Date: May 2016
 #include <util/message.h>
 #include <util/string2int.h>
 
+#include <json/json_parser.h>
+
 class basic_blockst
 {
 public:

src/goto-instrument/cover.h

@@ -22,6 +22,8 @@ class message_handlert;
 class coverage_goalst
 {
 public:
+  void get_coverage(const std::string &coverage,
+                    message_handlert &message_handler);
   void set_goals(std::string goal);
   bool is_existing_goal(source_locationt source_location);