move a variant of goto_instructiont::make_incomplete_goto

The particular variant is moved into the .cpp file to remove the need to
include std_code.h in the header file.

Author: kroening

src/goto-programs/goto_program.cpp

@@ -31,6 +31,13 @@ std::ostream &goto_programt::output(std::ostream &out) const
   return output(namespacet(symbol_tablet()), irep_idt(), out);
 }
 
+goto_programt::instructiont goto_programt::make_incomplete_goto(
+  const code_gotot &_code,
+  const source_locationt &l)
+{
+  return instructiont(_code, l, INCOMPLETE_GOTO, true_exprt(), {});
+}
+
 /// Writes to \p out a two/three line string representation of a given
 /// \p instruction. The output is of the format:
 /// ```

src/goto-programs/goto_program.h

@@ -23,6 +23,7 @@ Author: Daniel Kroening, kroening@kroening.com
 #include <util/namespace.h>
 #include <util/source_location.h>
 
+class code_gotot;
 enum class validation_modet;
 
 /// The type of an instruction in a GOTO program.
@@ -971,11 +972,8 @@ class goto_programt
   }
 
   static instructiont make_incomplete_goto(
-    const code_gotot &_code,
-    const source_locationt &l = source_locationt::nil())
-  {
-    return instructiont(_code, l, INCOMPLETE_GOTO, true_exprt(), {});
-  }
+    const code_gotot &,
+    const source_locationt & = source_locationt::nil());
 
   static instructiont make_goto(
     targett _target,