FEprogram_error vs FEprogram_error_noreturn

Hey,

I notice that there is a FEprogram_error and a FEprogram_error_noreturn
in src/c/error.d; however, it looks like these functions are identical
aside from their names.

I copied these to different files and diff'd them:

--- test        2017-06-28 15:39:32.199877688 -0500
+++ test2       2017-06-28 15:39:32.199877688 -0500
@@ -1,5 +1,5 @@
 void
-FEprogram_error(const char *s, int narg, ...)
+FEprogram_error_noreturn(const char *s, int narg, ...)
 {
   cl_object real_args, text;
   ecl_va_list args;

FEprogram_error_noreturn was added in commit 7d9fb8bb.  I think it was
added because FEprogram_error didn't have the noreturn attribute, so
FEprogram_error_noreturn was introduced with this attribute.  However,
it looks like FEprogram_error (and others) got this attribute in commit
790d466c.  (This all happened in Feb 2010.)

Currently in src/h/external.h:

extern ECL_API void FEprogram_error(const char *s, int narg, ...) ecl_attr_noreturn;
extern ECL_API void FEprogram_error_noreturn(const char *s, int narg, ...) ecl_attr_noreturn;

They are both used throughout src/c.

It seems like one of these should be removed.  If so, I can remove one
of them and change all of the calls to it.  I would say keep
FEprogram_error and remove FEprogram_error_noreturn.

If these changes are desired, then I can open up a new Merge Request
with these changes after my currently open Merge Request is done (to
avoid conflicts).

Cheers,
Kris Katterjohn