gnu: universal-ctags: Update to 5.9.20201018.0.

* gnu/packages/code.scm (universal-ctags): Update to 5.9.20201018.0.
[native-inputs]: Replace PACKCC with a forked origin.

gnu/packages/code.scm

@@ -339,25 +339,19 @@ features that are not supported by the standard @code{stdio} implementation.")
               "http://sourceforge.net/p/ctrio/git/ci/master/tree/README"))))
 
 (define-public universal-ctags
-  ;; The project is unable to decide whether to use 1.0 or 6.0 as the
-  ;; first public release version (it started as a fork of another ctags
-  ;; project that was on version 5.8), and five years later have been
-  ;; unable to tag a release.  Thus, we just take the master branch.
-  (let ((commit "0c78c0c4a68030df0d025c90bad291108b5e7107")
-        (revision "0"))
   (package
     (name "universal-ctags")
-      (version (git-version "0.0.0" revision commit))
+    (version "5.9.20201018.0")
     (source
      (origin
        (method git-fetch)
        (uri (git-reference
              (url "https://github.com/universal-ctags/ctags")
-               (commit commit)))
+             (commit (string-append "p" version))))
        (file-name (git-file-name name version))
        (sha256
         (base32
-           "0lnxc3kwi6srw0015m16vyjfdc7pdr9d1qzxjsbfv3c69ag87jhc"))
+         "174p1w20pl25k996hfw61inw4mqhskmmic1lyw2m65firmkyvs7x"))
        (modules '((guix build utils)))
        (snippet
         '(begin
@@ -396,7 +390,23 @@ features that are not supported by the standard @code{stdio} implementation.")
     (native-inputs
      `(("autoconf" ,autoconf)
        ("automake" ,automake)
-         ("packcc" ,packcc)
+       ;; XXX: Use ctags' own packcc fork even though we meticolously unbundle
+       ;; it above.  Mainly for historical reasons, and perhaps their changes
+       ;; get upstreamed in the future.
+       ("packcc"
+        ,(let ((commit "03402b79505dc0024f90d5bebfd7e5d3fb62da9a"))
+           (package
+             (inherit packcc)
+             (source (origin
+                       (method git-fetch)
+                       (uri (git-reference
+                             (url "https://github.com/universal-ctags/packcc")
+                             (commit commit)))
+                       (file-name (git-file-name "packcc-for-ctags"
+                                                 (string-take commit 7)))
+                       (sha256
+                        (base32
+                         "0vxpdk9l2lf7f32nx1p3b3xmw2kw2wp95vnf9bc4lyqrg69pblm0")))))))
        ("perl" ,perl)
        ("pkg-config" ,pkg-config)))
     (inputs
@@ -413,7 +423,7 @@ makes it easy for text editors and other tools to locate the indexed items.
 Universal Ctags improves on traditional ctags because of its multilanguage
 support, its ability for the user to define new languages searched by regular
 expressions, and its ability to generate emacs-style TAGS files.")
-      (license license:gpl2+))))
+    (license license:gpl2+)))
 
 (define-public withershins
   (package