xmedcon: fix cross

pkgs/by-name/xm/xmedcon/package.nix

@@ -1,6 +1,7 @@
 {
   stdenv,
   lib,
+  buildPackages,
   fetchurl,
   gtk3,
   glib,
@@ -31,6 +32,13 @@ stdenv.mkDerivation (finalAttrs: {
     wrapGAppsHook3
   ];
 
+  # xmedcon looks also for a host c compiler when cross-compiling
+  # otherwise you obtain following error message:
+  # "error: no acceptable C compiler found in $PATH"
+  depsBuildBuild = [
+    buildPackages.stdenv.cc
+  ];
+
   meta = {
     description = "Open source toolkit for medical image conversion";
     homepage = "https://xmedcon.sourceforge.net/";