Do not include libcouchbase_debug.so in binary packages

Change-Id: If7e308b360312cb442494931ba116edd1a145b8c
Reviewed-on: http://review.couchbase.org/24283
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Tested-by: Sergey Avseyev <sergey.avseyev@gmail.com>