Make some consts extern

Author: mgreter

src/error_handling.cpp

@@ -13,6 +13,11 @@ namespace Sass {
 
   namespace Exception {
 
+    sass::string def_msg("Invalid sass detected");
+    sass::string def_op_msg("Undefined operation");
+    sass::string def_op_null_msg("Invalid null operation");
+    sass::string def_nesting_limit("Code too deeply neested");
+
     Base::Base(SourceSpan pstate, sass::string msg, Backtraces traces)
     : std::runtime_error(msg.c_str()), msg(msg),
       prefix("Error"), pstate(pstate), traces(traces)

src/error_handling.hpp

@@ -21,10 +21,10 @@ namespace Sass {
 
   namespace Exception {
 
-    const sass::string def_msg = "Invalid sass detected";
-    const sass::string def_op_msg = "Undefined operation";
-    const sass::string def_op_null_msg = "Invalid null operation";
-    const sass::string def_nesting_limit = "Code too deeply neested";
+    extern sass::string def_msg;
+    extern sass::string def_op_msg;
+    extern sass::string def_op_null_msg;
+    extern sass::string def_nesting_limit;
 
     const sass::string msg_recursion_limit =
       "Too deep recursion detected. This can be caused by too deep level nesting.\n"