icu: make 58.2 coexists with 59.1

pkgs/development/libraries/icu/58.nix

@@ -0,0 +1,14 @@
+args @ { stdenv, fetchurl, fetchpatch, fixDarwinDylibNames }:
+let
+  keywordFix = fetchurl {
+    url = "http://bugs.icu-project.org/trac/changeset/39484?format=diff";
+    name = "icu-changeset-39484.diff";
+    sha256 = "0hxhpgydalyxacaaxlmaddc1sjwh65rsnpmg0j414mnblq74vmm8";
+  };
+in
+import ./base.nix {
+  version = "58.2";
+  sha256 = "036shcb3f8bm1lynhlsb4kpjm9s9c2vdiir01vg216rs2l8482ib";
+  patches = [ keywordFix ];
+  patchFlags = "-p4";
+} args

pkgs/development/libraries/icu/59.nix

@@ -0,0 +1,4 @@
+import ./base.nix {
+  version = "59.1";
+  sha256 = "1zkmbg2932ggvpgjp8pys0cj6z8bw087y8858009shkrjfpzscki";
+}

pkgs/development/libraries/icu/base.nix

@@ -1,8 +1,8 @@
+{ version, sha256, patches ? [], patchFlags ? "" }:
 { stdenv, fetchurl, fetchpatch, fixDarwinDylibNames }:
 
 let
   pname = "icu4c";
-  version = "59.1";
 in
 stdenv.mkDerivation {
   name = pname + "-" + version;
@@ -10,7 +10,7 @@ stdenv.mkDerivation {
   src = fetchurl {
     url = "http://download.icu-project.org/files/${pname}/${version}/${pname}-"
       + (stdenv.lib.replaceChars ["."] ["_"] version) + "-src.tgz";
-    sha256 = "1zkmbg2932ggvpgjp8pys0cj6z8bw087y8858009shkrjfpzscki";
+    inherit sha256;
   };
 
   outputs = [ "out" "dev" ];
@@ -25,6 +25,8 @@ stdenv.mkDerivation {
     echo Source root reset to ''${sourceRoot}
   '';
 
+  inherit patchFlags patches;
+
   preConfigure = ''
     sed -i -e "s|/bin/sh|${stdenv.shell}|" configure
   '' + stdenv.lib.optionalString stdenv.isArm ''