gnu: Add texlive-barr.

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

gnu/packages/tex.scm

@@ -1277,6 +1277,24 @@ (define-public texlive-autoaligne
 math expressions.")
     (license license:lppl1.3c)))
 
+(define-public texlive-barr
+  (package
+    (name "texlive-barr")
+    (version (number->string %texlive-revision))
+    (source (texlive-origin
+             name version
+             (list "doc/generic/barr/" "tex/generic/barr/")
+             (base32
+              "1l532g0nxigbllv2lf74bwx78sf4jsfr1cad0hpq7i7kq820wbii")))
+    (outputs '("out" "doc"))
+    (build-system texlive-build-system)
+    (home-page "https://ctan.org/pkg/diagxy")
+    (synopsis "Diagram macros by Michael Barr")
+    (description
+     "Diagxy is a general diagramming package, useful for diagrams in a number
+of mathematical disciplines.")
+    (license license:lppl1.3+)))
+
 (define-public texlive-dosepsbin
   (package
     (name "texlive-dosepsbin")