utils: Add Mu::canonicalize_filename

We need it for unit-tests

lib/utils/mu-utils.cc

@@ -33,7 +33,7 @@
 #include <glib/gprintf.h>
 
 #include "mu-utils.hh"
-
+#include "mu-util.h"
 
 using namespace Mu;
 
@@ -447,6 +447,21 @@ Mu::size_to_string (const std::string& val, bool is_first)
 	return str;
 }
 
+
+std::string
+Mu::canonicalize_filename(const std::string& path, const std::string& relative_to)
+{
+        char *fname = mu_canonicalize_filename (
+                path.c_str(),
+                relative_to.empty() ? NULL : relative_to.c_str());
+
+        std::string rv{fname};
+        g_free (fname);
+
+        return rv;
+}
+
+
 void
 Mu::assert_equal(const std::string& s1, const std::string& s2)
 {