Add LOG_TO_SINK_IF and DLOG_TO_SINK

[sukanth2705]

Added LOG_TO_SINK_IF and DLOG_TO_SINK in logging.h

This PR closes #568

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[sukanth2705]

@sergiud Can u take a look?

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 64.03%. Comparing base (570c7e4) to head (18bbf15). Report is 6 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1117      +/-   ##
==========================================
- Coverage   64.04%   64.03%   -0.02%     
==========================================
  Files          20       20              
  Lines        2578     2580       +2     
  Branches      898      908      +10     
==========================================
+ Hits         1651     1652       +1     
- Misses        662      663       +1     
  Partials      265      265              

Files	Coverage Δ
src/glog/logging.h	83.60% <ø> (ø)

... and 1 file with indirect coverage changes