gtest: Add support for std::unique_ptr bool conversion

This cherry-picks the new AssertionResult constructor that supports
contextual conversion to bool, found in
https://github.com/google/googletest/commit/8120f66c3249e253f03fdb48bee7e528bc038d31

This is needed to support a libchrome uprev.

BUG: 28985443
TEST: All tests in libchrome_test pass on dragonboard-eng build

Change-Id: I59bc96f785e97a1c6abfa492f72278cb99213303
2 files changed