6914: Fix windows check formatting script

Reviewed-by: hirt, ghb

scripts/checkformatting.bat

@@ -1,15 +1,15 @@
 @echo off
 echo "======== Building p2 repo ==================="
 cd releng\third-party
-mvn p2:site
+call mvn p2:site || EXIT /B 1
 echo "======== Starting p2 repo ==================="
 start /B cmd /C "mvn jetty:run"
 cd ..\..\core
 echo "======== Installing core ===================="
-call mvn install
+call mvn install || EXIT /B 2
 echo "======== Running spotless for core =========="
-mvn spotless:check
+call mvn spotless:check || EXIT /B 3
 echo "======== Running spotless for application ==="
 cd ..
-mvn -Puitests spotless:check
+call mvn -Puitests spotless:check || EXIT /B 4
 echo "======== Finished ==========================="