Add local.properties.sample for building acl by ndk.

Author: zhengshuxin

android/acl_ndk20/local.properties.sample

@@ -0,0 +1,11 @@
+## This file must *NOT* be checked into Version Control Systems,
+# as it contains information specific to your local configuration.
+#
+# Location of the SDK. This is only used by Gradle.
+# For customization when using a Version Control System, please read the
+# header note.
+#Fri Mar 13 10:36:12 CST 2020
+ndk.dir=/opt/soft/android/ndk
+sdk.dir=/opt/soft/android/sdk
+cmake.dir=/opt/soft/android/sdk/cmake/3.10.2.4988404
+