scripts/make.fsx: cosmetic, use longer flag name

And also use dash prefix instead of slash, which is more
crossplatform friendly (because in Unix something that starts
with a slash could be a path).

scripts/make.fsx

@@ -157,7 +157,7 @@ let BuildSolution
         if buildTool.StartsWith "dotnet" then
             sprintf "--configuration %s" (binaryConfig.ToString())
         else
-            sprintf "/p:Configuration=%s" (binaryConfig.ToString())
+            sprintf "-property:Configuration=%s" (binaryConfig.ToString())
 
     let defineConstantsFromBuildConfig =
         match buildConfigContents |> Map.tryFind "DefineConstants" with
@@ -191,11 +191,11 @@ let BuildSolution
             | "xbuild", _ ->
                 // xbuild: legacy of the legacy!
                 // see https://github.com/dotnet/sdk/issues/9562
-                sprintf "%s /p:DefineConstants=\"%s\"" configOption (String.Join(semiColonEscaped, defineConstants))
+                sprintf "%s -property:DefineConstants=\"%s\"" configOption (String.Join(semiColonEscaped, defineConstants))
             | builtTool, Misc.Platform.Windows when buildTool.ToLower().Contains "msbuild" ->
-                sprintf "%s /p:DefineConstants=\"%s\"" configOption (String.Join(semiColon, defineConstants))
+                sprintf "%s -property:DefineConstants=\"%s\"" configOption (String.Join(semiColon, defineConstants))
             | _ ->
-                sprintf "%s /p:DefineConstants=\\\"%s\\\"" configOption (String.Join(semiColon, defineConstants))
+                sprintf "%s -property:DefineConstants=\\\"%s\\\"" configOption (String.Join(semiColon, defineConstants))
         else
             configOption
     let buildArgs = sprintf "%s %s %s %s"