Bug 696317

It seems since Ghostscript 9.18
e_Fatal e_ExecStackUnderflow e_NeedInput
are missing (and many more).

Those existed in Ghostscript 9.16 as follows:
---------------------------------------------------------------------------
$ egrep 'define e_Fatal|define e_ExecStackUnderflow|define e_NeedInput' \
  ghostscript-9.16/psi/ierrors.h
#define e_Fatal (-100)
#define e_ExecStackUnderflow (-104)
#define e_NeedInput (-106)
---------------------------------------------------------------------------

In Ghostscript 9.18 those error defines do no longer exist.
A diff of psi/ierrors.h between Ghostscript 9.16 and Ghostscript 9.18
shows that many such error defines do no longer exist.
Currently I do not know hwy they are dropped in Ghostscript 9.18.

As a consequence in the openSUSE Build Service
with Ghostscript 9.18 plus the fix for
http://bugs.ghostscript.com/show_bug.cgi?id=696301
libspectre build fails currently with
---------------------------------------------------------------------------
spectre-gs.c: In function 'critic_error_code':
spectre-gs.c:46:9: error: 'e_Fatal' undeclared (first use in this function)
    case e_Fatal:
         ^
spectre-gs.c:46:9: note: each undeclared identifier is reported only
 once for each function it appears in
spectre-gs.c:51:9: error: 'e_ExecStackUnderflow' undeclared (first use
 in this function)
    case e_ExecStackUnderflow:
         ^
spectre-gs.c: In function 'spectre_gs_process':
spectre-gs.c:112:20: error: 'e_NeedInput' undeclared (first use in
 this function)
    error = error == e_NeedInput ? 0 : error;
                     ^
---------------------------------------------------------------------------

At least e_NeedInput is still mentioned for Ghostscript 9.18
in doc/API.htm and doc/Develop.htm and it is used in
toolbin/halftone/gen_stochastic/gen_stochastic.c