Add OWNERS in tools/loganalysis

* Owners are selected from top CL approvals or owners.
  They will be suggested to review/approve future CLs.
* OWNERS files are recognized by the new find-owners plugin, see .md files in
  https://gerrit.googlesource.com/plugins/find-owners/+/master/src/main/resources/Documentation/

Test: build/make/tools/checkowners.py -c -v OWNERS
Change-Id: I774442b315d32aff99574c48616b1a954719b95b

OWNERS

+erowe@google.com
+guangzhu@google.com
+paulduffin@google.com
+siniavine@google.com
+tobiast@google.com