Allow to run 'make check' without plugins

Because of built-in 'select' plugin, most of examples and cbc can be
built without dynamic plugins

Change-Id: Ie76692d1740228c17edd75763e531fb3c429780c
Reviewed-on: http://review.couchbase.org/28248
Tested-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>