windows.mingw_w64_headers: Add libc assert, improve meta block

pkgs/os-specific/windows/mingw-w64/default.nix

@@ -35,7 +35,7 @@ stdenv.mkDerivation {
   enableParallelBuilding = true;
 
   nativeBuildInputs = [ autoreconfHook ];
-  buildInputs = [ windows.mingw_w64_headers ];
+  buildInputs = [ mingw_w64_headers ];
   hardeningDisable = [
     "stackprotector"
     "fortify"

pkgs/os-specific/windows/mingw-w64/headers.nix

@@ -4,7 +4,10 @@
   fetchurl,
   crt ? stdenvNoCC.hostPlatform.libc,
 }:
-
+assert lib.assertOneOf "crt" crt [
+  "msvcrt"
+  "ucrt"
+];
 stdenvNoCC.mkDerivation (finalAttrs: {
   pname = "mingw_w64-headers";
   version = "12.0.0";
@@ -23,9 +26,17 @@ stdenvNoCC.mkDerivation (finalAttrs: {
   '';
 
   meta = {
-    downloadPage = "https://sourceforge.net/projects/mingw/files/Other/UserContributed/regex/";
+    homepage = "https://www.mingw-w64.org/";
+    downloadPage = "https://sourceforge.net/projects/mingw-w64/files/mingw-w64/mingw-w64-release/";
     description = "Collection of headers and libraries for building native Windows applications";
-    license = lib.licenses.publicDomain;
+    license = with lib.licenses; [
+      # Primarily under
+      zpl21
+      # A couple files
+      mit
+      # Certain headers imported from Wine
+      lgpl21Plus
+    ];
     platforms = lib.platforms.windows;
     teams = [ lib.teams.windows ];
   };