CI/cppcheck: ignore errors from _deps (googletest).

Unfortunately current cppcheck does not allow us to ignore those files
completely when we use the useful --project option.
9 jobs for mh_optimization in 3 minutes and 38 seconds (queued for 4 seconds)
Status Name Job ID Coverage
  Test
passed clang-c++11 #133317
Linux

00:03:37

failed cppcheck #133319
Linux

00:00:18

passed doc #133324
Linux

00:00:06

passed gcc-c++11 #133316
Linux

00:03:16

passed macos-c++11 #133318
Apple

00:02:08

passed VS2015-32-bit #133323
VS2015

00:01:26

passed VS2015-64-bit #133322
VS2015

00:01:27

passed VS2017-32-bit #133321
VS2017

00:01:35

passed VS2017-64-bit #133320
VS2015

00:01:53

 
Name Stage Failure
failed
cppcheck Test
==============================================================================
CPPCHECK Summary
==============================================================================


Total CPPCHECK error Count is 93, which is too High! CPPCHECK Run failed

Cleaning up file based variables
ERROR: Job failed: exit status 1