gnu: ghostscript-with-cups: Turn into a public variable.

Tris allows Hydra/Cuirass to pick it up and to build its replacement.
Failing that, users have to build "ghostscript-with-cups-9.22" from
source.

* gnu/packages/cups.scm (ghostscript/cups): Move to 'ghostscript.scm'.
(cups-filters)[inputs]: Remove 'force'.
* gnu/packages/ghostscript.scm (ghostscript/cups): New variable.

gnu/packages/cups.scm

@@ -46,14 +46,6 @@
   #:use-module (gnu packages pkg-config)
   #:use-module (gnu packages tls))
 
-;; Delay to avoid module circularity problems.
-(define ghostscript/cups
-  (delay
-    (package/inherit ghostscript
-      (name "ghostscript-with-cups")
-      (inputs `(("cups" ,cups-minimal)
-                ,@(package-inputs ghostscript))))))
-
 (define-public cups-filters
   (package
     (name "cups-filters")
@@ -146,7 +138,7 @@
        ("fontconfig"   ,fontconfig)
        ("freetype"     ,freetype)
        ("font-dejavu"  ,font-dejavu) ; also needed by test suite
-       ("ghostscript"  ,(force ghostscript/cups))
+       ("ghostscript"  ,ghostscript/cups)
        ("ijs"          ,ijs)
        ("dbus"         ,dbus)
        ("lcms"         ,lcms)

gnu/packages/ghostscript.scm

@@ -26,6 +26,7 @@
   #:use-module (gnu packages)
   #:use-module (gnu packages autotools)
   #:use-module (gnu packages compression)
+  #:use-module (gnu packages cups)
   #:use-module (gnu packages fontutils)
   #:use-module (gnu packages image)
   #:use-module (gnu packages perl)
@@ -281,6 +282,12 @@ output file formats and printers.")
               ("libxt" ,libxt)
               ,@(package-inputs ghostscript)))))
 
+(define-public ghostscript/cups
+  (package/inherit ghostscript
+    (name "ghostscript-with-cups")
+    (inputs `(("cups" ,cups-minimal)
+              ,@(package-inputs ghostscript)))))
+
 (define-public ijs
   (package
    (name "ijs")