run clang-tidy

[sergiud]

Define clang-tidy and clang-format configs based on google-* checks and Google style.

[codecov-commenter]

Codecov Report

Merging #765 (666622c) into master (d09b999) will decrease coverage by 0.18%.
The diff coverage is 40.54%.

@@            Coverage Diff             @@
##           master     #765      +/-   ##
==========================================
- Coverage   73.01%   72.83%   -0.19%     
==========================================
  Files          17       17              
  Lines        3217     3228      +11     
==========================================
+ Hits         2349     2351       +2     
- Misses        868      877       +9     

Impacted Files	Coverage Δ
src/signalhandler.cc	6.45% <0.00%> (-0.09%)	⬇️
src/vlog_is_on.cc	70.22% <0.00%> (-1.09%)	⬇️
src/logging.cc	73.60% <33.33%> (-0.27%)	⬇️
src/symbolize.cc	64.11% <33.33%> (ø)
src/demangle.cc	97.48% <100.00%> (+<0.01%)	⬆️
src/stacktrace_libunwind-inl.h	90.00% <100.00%> (ø)
src/stacktrace_x86_64-inl.h	92.85% <100.00%> (ø)

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