Sets LOCAL_PATH in platform_tests.mk.

This is used in package-modules.mk to get this module's path.

Bug: 152799773
Test: Inspect module-info.json for 'platform_tests'
Change-Id: I5a9d3c4aaa500721b4b1e471ec28fc12e8f406ab
diff --git a/build/tasks/platform_tests.mk b/build/tasks/platform_tests.mk
index 9c88a6c..1bed4de 100644
--- a/build/tasks/platform_tests.mk
+++ b/build/tasks/platform_tests.mk
@@ -16,7 +16,8 @@
 # based on the configuration.
 #
 
-include $(call my-dir)/tests/platform_test_list.mk
+LOCAL_PATH := $(call my-dir)
+include $(LOCAL_PATH)/tests/platform_test_list.mk
 -include $(wildcard vendor/*/build/tasks/tests/platform_test_list.mk)
 
 my_modules := $(platform_tests)