Skip log matching when EXPECT_SPURIOUS_SYSCALLS=ON

[GBuella]

It is too hard to predict what is going to end up in the logs
with ASAN, gcov, etc...

The logs are still checked while doing tests without EXPECT_SPURIOUS_SYSCALLS, so this should not be a problem. I gave up on matching logs after this build: https://travis-ci.org/GBuella/syscall_intercept/jobs/249368556

Ref: #7

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This change is 

[codecov-io]

Codecov Report

Merging #32 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #32   +/-   ##
=======================================
  Coverage   56.93%   56.93%           
=======================================
  Files          18       18           
  Lines        1486     1486           
  Branches      413      413           
=======================================
  Hits          846      846           
  Misses        440      440           
  Partials      200      200

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[krzycz]

Reviewed 2 of 2 files at r1.
Review status: all files reviewed at latest revision, all discussions resolved.

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Comments from Reviewable

[sarahjelinek]

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Reviewed 2 of 2 files at r1.
Review status: all files reviewed at latest revision, all discussions resolved, all commit checks successful.

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Comments from Reviewable