libssh2: Remove crossAttrs

- --with-<lib> stuff isn't needed with new default

 - `mingw_w64` probably also isn't needed, but kept with better code
   just in case.

pkgs/development/libraries/libssh2/default.nix

@@ -12,22 +12,8 @@ stdenv.mkDerivation rec {
 
   outputs = [ "out" "dev" "devdoc" ];
 
-  buildInputs = [ openssl zlib ];
-
-  crossAttrs = {
-    # link against cross-built libraries
-    configureFlags = [
-      "--with-openssl"
-      "--with-libssl-prefix=${openssl.crossDrv}"
-      "--with-libz"
-      "--with-libz-prefix=${zlib.crossDrv}"
-    ];
-  } // stdenv.lib.optionalAttrs (hostPlatform.libc == "msvcrt") {
-    # mingw needs import library of ws2_32 to build the shared library
-    preConfigure = ''
-      export LDFLAGS="-L${windows.mingw_w64}/lib $LDFLAGS"
-    '';
-  };
+  buildInputs = [ openssl zlib ]
+    ++ stdenv.lib.optional hostPlatform.isMinGW windows.mingw_w64;
 
   meta = {
     description = "A client-side C library implementing the SSH2 protocol";