Check for new line in end of pg file on -printconfiguration insert

Change-Id: I30b1caa8ee77296f294cf08776a8d01c02e64989
diff --git a/tools/as_utils.py b/tools/as_utils.py
index 10fb29f..5f224a6 100644
--- a/tools/as_utils.py
+++ b/tools/as_utils.py
@@ -126,6 +126,9 @@
     for line in lines:
       if '-printconfiguration' not in line:
         f.write(line)
+    # Check that there is a line-break at the end of the file or insert one.
+    if lines[-1].strip():
+      f.write('\n')
     f.write('-printconfiguration {}\n'.format(destination))
 
 def FindProguardConfigurationFile(app, config, checkout_dir):