phosphor-logging: srcrev bump 30047bf964..31552c05e2

Patrick Venture (5):
      add sdjournal interface to inject tests
      test: use only one main library
      bugfix: add fixes to mock class
      bugfix: rename method to match implementation
      test: add test to force building of sdjournal mock

(From meta-phosphor rev: 17316b6d4d13da98b2f4feee489cb85d37547e5d)

Change-Id: I5ad126a739cad075832efed6204bc97c13cbb3ca
Signed-off-by: Andrew Geissler <openbmcbump-github@yahoo.com>
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>