build-unit-test-docker: Fix googletest with c++17

If you don't compile with c++17 support at build time, then some of the
matchers like those of std::string_view don't get linked into gmock
correctly.

Change-Id: I8d89cfafa46037ef5829eecfbf3506d9fefcb6a1
Signed-off-by: William A. Kennington III <wak@google.com>
1 file changed