openssl: fix cross compile (perl)

Fixes issue #50921. Build result was depending on build perl instead of
host perl which broke cross compilation.

pkgs/development/libraries/openssl/default.nix

@@ -87,6 +87,7 @@ let
     '' +
     ''
       mkdir -p $bin
+      substituteInPlace $out/bin/c_rehash --replace ${buildPackages.perl} ${perl}
       mv $out/bin $bin/
 
       mkdir $dev