libreoffice(-still): fixup build by using older icu

It's slightly risky, as many dependencies use the newer icu already.
-fresh seems OK without such changes.

pkgs/top-level/all-packages.nix

@@ -15357,6 +15357,7 @@ with pkgs;
     harfbuzz = harfbuzz.override {
       withIcu = true; withGraphite2 = true;
     };
+    icu = icu58;
     # checking whether g++ supports C++14 or C++11... configure: error: no
     stdenv = overrideCC stdenv gcc5;
   });