[6model] Added annotations to exception throwers.

This clears up several compiler warnings.

Author: chromatic

src/6model/reprs/KnowHOWREPR.c

@@ -45,6 +45,7 @@ static INTVAL defined(PARROT_INTERP, PMC *obj) {
 }
 
 /* Helper to die because this type doesn't support attributes. */
+PARROT_DOES_NOT_RETURN
 static void die_no_attrs(PARROT_INTERP) {
     Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_INVALID_OPERATION,
             "KnowHOWREPR representation does not support attribute storage");

src/6model/reprs/P6int.c

@@ -44,6 +44,7 @@ static INTVAL defined(PARROT_INTERP, PMC *obj) {
 }
 
 /* Helper to die because this type doesn't support attributes. */
+PARROT_DOES_NOT_RETURN
 static void die_no_attrs(PARROT_INTERP) {
     Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_INVALID_OPERATION,
             "P6str representation does not support attribute storage");

src/6model/reprs/P6num.c

@@ -44,6 +44,7 @@ static INTVAL defined(PARROT_INTERP, PMC *obj) {
 }
 
 /* Helper to die because this type doesn't support attributes. */
+PARROT_DOES_NOT_RETURN
 static void die_no_attrs(PARROT_INTERP) {
     Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_INVALID_OPERATION,
             "P6str representation does not support attribute storage");

src/6model/reprs/P6opaque.c

@@ -391,7 +391,8 @@ static INTVAL defined(PARROT_INTERP, PMC *obj) {
     return instance->spill != NULL;
 }
 
-/* Helper for complaining about attrbiute access errors. */
+/* Helper for complaining about attribute access errors. */
+PARROT_DOES_NOT_RETURN
 static void no_such_attribute(PARROT_INTERP, char *action, PMC *class_handle, STRING *name) {
     Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_INVALID_OPERATION,
             "Can not %s non-existant attribute '%Ss' on class '%Ss'",

src/6model/reprs/P6str.c

@@ -44,6 +44,7 @@ static INTVAL defined(PARROT_INTERP, PMC *obj) {
 }
 
 /* Helper to die because this type doesn't support attributes. */
+PARROT_DOES_NOT_RETURN
 static void die_no_attrs(PARROT_INTERP) {
     Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_INVALID_OPERATION,
             "P6str representation does not support attribute storage");

src/6model/reprs/Uninstantiable.c

@@ -42,6 +42,7 @@ static INTVAL defined(PARROT_INTERP, PMC *obj) {
 }
 
 /* Helper to die because this type doesn't support attributes. */
+PARROT_DOES_NOT_RETURN
 static void die_no_attrs(PARROT_INTERP) {
     Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_INVALID_OPERATION,
             "Uninstantiable representation does not support attribute storage");