Revert "Add libgtest_prod."

Darwin doesn't support our implementation of header only static
libraries. Reverting to fix the build until we find a solution.

This reverts commit 18d1e9ca582db6db2fcf64876b0d59e47a026adc.

Change-Id: I5c878280b909dd7c1649b3f4a3c090d10d046046
1 file changed