gnu: Add texlive-custom-bib.

* gnu/packages/tex.scm (texlive-custom-bib): New variable.

gnu/packages/tex.scm

@@ -7232,6 +7232,38 @@ for structuring exercises, aggregating points, and displaying a grading table,
 as well as several macros for easier math mode usage.")
     (license license:expat)))
 
+(define-public texlive-custom-bib
+  (package
+    (name "texlive-custom-bib")
+    (version (number->string %texlive-revision))
+    (source (texlive-origin
+             name version
+             (list "doc/latex/custom-bib/"
+                   "source/latex/custom-bib/"
+                   "tex/latex/custom-bib/")
+             (base32
+              "1hzy0j9k55ygkzvgs3y2jz435267l3g4isqynr64978zhyqybqpd")))
+    (outputs '("out" "doc"))
+    (build-system texlive-build-system)
+    (arguments
+     (list #:phases
+           #~(modify-phases %standard-phases
+               ;; The installation process requires ".mbs" files to be
+               ;; available when generating the package.  Extend TEXINPUTS to
+               ;; include their location.
+               (add-before 'build 'extend-texinputs
+                 (lambda _
+                   (setenv "TEXINPUTS"
+                           (string-append (getcwd)
+                                          "/tex/latex/custom-bib/:")))))))
+    (home-page "https://ctan.org/pkg/custom-bib")
+    (synopsis "Customised BibTeX styles")
+    (description
+     "This package generates customized BibTeX bibliography styles from
+a generic file using @code{docstrip} driven by parameters generated by a menu
+application.  It includes support for the Harvard style of citations.")
+    (license license:lppl)))
+
 (define-public texlive-customdice
   (package
     (name "texlive-customdice")