MB-11846: Add workaround for broken builders

According to MB-11846 we have some misconfigured vm's unable to
compile the source code without enabling optimization. This
patch introduce a workaround to enable the optimization of the
breakdancer tests until the vm's is fixed. To use the workaround
define COUCHBASE_OPTIMIZE_BREAKDANCER_TEST during compilation.

Add -D CMAKE_C_FLAGS=-DCOUCHBASE_OPTIMIZE_BREAKDANCER_TEST to
the command line when invoking cmake.

Change-Id: I067548b39be9f52951afed0c30221e1d77926b93
Reviewed-on: http://review.couchbase.org/40165
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>