tree-wide: replace uses of splitString "." with lib.versions

Quoting from the splitString docstring:

   NOTE: this function is not performant and should never be used.

This replaces trivial uses of splitString for splitting version
strings with the (potentially builtin) splitVersion.

pkgs/misc/emulators/epsxe/default.nix

@@ -8,7 +8,7 @@ stdenv.mkDerivation rec {
   version = "2.0.5";
 
   src = let
-    version2 = concatStrings (splitString "." version);
+    version2 = replaceStrings ["."] [""] version;
     platform = "linux" + (optionalString stdenv.is64bit "_x64");
   in fetchurl {
     url = "https://www.epsxe.com/files/ePSXe${version2}${platform}.zip";