Made some classes have file linkage in tablet/compaction_policy.cc
Made some classes have file linkage in tablet/compaction_policy.cc

Some utility classes (such as the upper bound calculator and the
KnapsackTraits class) were not in an anonymous namespace, even though
they should be.

Change-Id: Iefdc3f919248933affae3ba5db8ca7c490068972
Reviewed-on: http://gerrit.ent.cloudera.com:8080/3334
Reviewed-by: Todd Lipcon <2c763d726a8c2f6afda9be7e0e56a2caa6bb5e6b@cloudera.com>
Tested-by: jenkins

cloudera/kudu,cloudera/kudu,helifu/kudu,andrwng/kudu,InspurUSA/kudu,helifu/kudu,EvilMcJerkface/kudu,cloudera/kudu,helifu/kudu,InspurUSA/kudu,EvilMcJerkface/kudu,InspurUSA/kudu,InspurUSA/kudu,cloudera/kudu,andrwng/kudu,InspurUSA/kudu,andrwng/kudu,helifu/kudu,andrwng/kudu,helifu/kudu,EvilMcJerkface/kudu,EvilMcJerkface/kudu,InspurUSA/kudu,andrwng/kudu,andrwng/kudu,andrwng/kudu,InspurUSA/kudu,EvilMcJerkface/kudu,EvilMcJerkface/kudu,EvilMcJerkface/kudu,EvilMcJerkface/kudu,cloudera/kudu,helifu/kudu,cloudera/kudu,InspurUSA/kudu,helifu/kudu,cloudera/kudu,helifu/kudu,EvilMcJerkface/kudu,helifu/kudu,InspurUSA/kudu,andrwng/kudu,cloudera/kudu,cloudera/kudu,andrwng/kudu