Add empty.mk

Bug: 181614552
Test: n/a
Change-Id: Ib624af5b230d4627476e38e62ba8389e19d357da
diff --git a/gsi/build_with_kernel/empty.mk b/gsi/build_with_kernel/empty.mk
new file mode 100644
index 0000000..cd4031a
--- /dev/null
+++ b/gsi/build_with_kernel/empty.mk
@@ -0,0 +1 @@
+# an empty makefile