gnu: openjdk: Disallow references to the JDK used for build.

This ensures JDKs don't unintentionally keep references to the one used
to build them, as reported at <https://issues.guix.gnu.org/31719#7> and
fixed by 97a43db8b4.

* gnu/packages/java.scm (icedtea-8)[arguments]: Add #:disallowed-references.
(openjdk9)[arguments]: Likewise.
(openjdk10)[arguments]: Likewise.
(openjdk11)[arguments]: Likewise.

gnu/packages/java.scm

@@ -1749,6 +1749,9 @@ (define-public icedtea-8
          ((guix build ant-build-system)
           (guix build syscalls)
           ,@%gnu-build-system-modules)
+
+         #:disallowed-references ((,icedtea-7 "jdk"))
+
          ,@(substitute-keyword-arguments (package-arguments icedtea-7)
              ((#:modules modules)
               `((guix build utils)
@@ -1902,6 +1905,9 @@ (define-public openjdk9
        #:imported-modules
        ((guix build syscalls)
         ,@%gnu-build-system-modules)
+
+       #:disallowed-references (,icedtea-8 (,icedtea-8 "jdk"))
+
        #:phases
        (modify-phases %standard-phases
          (add-after 'patch-source-shebangs 'fix-java-shebangs
@@ -2097,7 +2103,9 @@ (define-public openjdk10
                        "--with-libjpeg=system"
                        "--with-native-debug-symbols=zipped"
                        (string-append "--prefix=" (assoc-ref outputs "out")))
-               #t))))))
+               #t))))
+       ((#:disallowed-references _ '())
+        `(,openjdk9 (,openjdk9 "jdk")))))
     (native-inputs
      `(("openjdk9" ,openjdk9)
        ("openjdk9:jdk" ,openjdk9 "jdk")
@@ -2127,6 +2135,9 @@ (define-public openjdk11
     (arguments
      `(#:imported-modules ((guix build syscalls)
                            ,@%gnu-build-system-modules)
+
+       #:disallowed-references (,openjdk10 (,openjdk10 "jdk"))
+
        #:tests? #f; requires jtreg
        ;; TODO package jtreg
        #:configure-flags