Make gtest_main include gtest shim (#4295)
Make gtest_main include gtest shim (#4295)

For consistency with other usage throughout the project and to isolate
some of the shimming we have to do internally due to different include
paths.
iree-org/iree,google/iree,google/iree,google/iree,google/iree,google/iree,iree-org/iree,iree-org/iree,iree-org/iree,google/iree,iree-org/iree,iree-org/iree,google/iree,iree-org/iree