gnu: Remove redundant icu4c@64 package.

* gnu/packages/icu4c.scm (icu4c-64): Remove variable.
* gnu/packages/chromium.scm (ungoogled-chromium)[inputs]: Change ICU4C-64 to ICU4C.

gnu/packages/chromium.scm

@@ -714,11 +714,7 @@ from forcing GEXP-PROMISE."
        ("glib" ,glib)
        ("gtk+" ,gtk+)
        ("harfbuzz" ,harfbuzz)
-
-       ;; Build against ICU 64 to prevent a localization problem in version 75
-       ;; and later: <https://github.com/Eloston/ungoogled-chromium/issues/778>.
-       ("icu4c" ,icu4c-64)
-
+       ("icu4c" ,icu4c)
        ("jsoncpp" ,jsoncpp)
        ("lcms" ,lcms)
        ("libevent" ,libevent)

gnu/packages/icu4c.scm

@@ -85,22 +85,6 @@ C/C++ part.")
    (license x11)
    (home-page "http://site.icu-project.org/")))
 
-(define-public icu4c-64
-  (package
-    (inherit icu4c)
-    (version "64.2")
-    (source (origin
-              (inherit (package-source icu4c))
-              (uri (string-append
-                    "http://download.icu-project.org/files/icu4c/" version "/icu4c-"
-                    (string-map (lambda (x) (if (char=? x #\.) #\_ x)) version)
-                    "-src.tgz"))
-              (sha256
-               (base32 "0v0xsf14xwlj125y9fd8lrhsaych4d8liv8gr746zng6g225szb2"))))
-    (native-inputs
-     `(;; For tests.
-       ("python" ,python)))))
-
 (define-public java-icu4j
   (package
     (name "java-icu4j")