add unittest for group_concat built-in func in sqlite after CL# 38176

after CL https://android-git.corp.google.com/g/#change,38176, behavior of
sqlite func group_concat changed. add a unittest to test that.
1 file changed
tree: a60007cfbb57190ebbb9e9802af85e2927636243
  1. tests/
  2. tools/
  3. .gitignore
  4. Android.mk