Fix autoninja && chrome on failed builds

A handy usage pattern for autoninja.bat that I was not aware of is to go

    autoninja -C out\Default chrome && chrome

This will build chrome and then run it, but only run it if the build
succeeds. The addition of post_build_ninja_summary.py broke this by
losing the error code. This change fixes it by using black magic to
set an error code in the failure case.

Bug: chromium:787983
Change-Id: Ib87fd1799816e19d56de76e08e0f9688be903d80
Reviewed-on: https://chromium-review.googlesource.com/916705Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Bruce Dawson <brucedawson@chromium.org>

autoninja

@@ -10,7 +10,13 @@
 command=$(python $(dirname -- "$0")/autoninja.py "$@")
 echo $command
 $command
-if [ $? -eq 0 ] && [ "$NINJA_SUMMARIZE_BUILD" == "1" ]; then
-  python $(dirname -- "$0")/post_build_ninja_summary.py $@
+if [ $? -eq 0 ]; then
+  if [ "$NINJA_SUMMARIZE_BUILD" == "1" ]; then
+    python $(dirname -- "$0")/post_build_ninja_summary.py $@
+  fi
+  exit
 fi
+# Return an error code of 1 so that if a developer types:
+# "autoninja chrome && chrome" then chrome won't run if the build fails.
+exit 1
 

autoninja.bat

@@ -8,4 +8,8 @@ REM Also print it to reassure that the right settings are being used.
 FOR /f "usebackq tokens=*" %%a in (`python %~dp0autoninja.py "%*"`) do echo %%a & %%a
 @if errorlevel 1 goto buildfailure
 @if "%NINJA_SUMMARIZE_BUILD%" == "1" python %~dp0post_build_ninja_summary.py %*
+exit /b
 :buildfailure
+REM Return an error code of 1 so that if a developer types:
+REM "autoninja chrome && chrome" then chrome won't run if the build fails.
+cmd /c exit 1