Enable parallel compilation with MinGW and fix gmtime_s detection

[eramongodb]

Verified by this patch.

Increases the speed of MinGW compilation on Windows by passing the -j flag to CMake MinGW Make. No limit on concurrent processes is set in order to maximize use of the resources available on Evergreen.

As a drive-by fix, updated feature detection for MSVC-style gmtime_s in kms_request.c to be consistent with the logic used in bson-iso8601.c, as it may otherwise fail when building with MinGW depending on the build configurations used.

[eramongodb]

Fixed PR description to indicate the -j flag is being passed to MinGW Make, not CMake. System-available CMake versions on Windows distros are currently 3.11, which do not support -j yet (introduced in 3.12).

As an additional drive-by fix, added default CMAKE_CXX_STANDARD to CMake configs when C++ is enabled to address MinGW failure to compile cpp_check.cpp presumably due to pre-C++11 defaults. Because test-libmongoc happens to be generated prior to build failure, and the BAT file does not have error handling to exit on failure, the task happened to continue successfully. This will be addressed in a separate PR.

Verified by this patch.

[codecov-commenter]

Codecov Report

Merging #1185 (80333a1) into master (80333a1) will not change coverage.
The diff coverage is n/a.

❗ Current head 80333a1 differs from pull request most recent head dcc48f8. Consider uploading reports for the commit dcc48f8 to get more accurate results

@@           Coverage Diff           @@
##           master    #1185   +/-   ##
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  Coverage   63.72%   63.72%           
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  Files         328      328           
  Lines       84343    84343           
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  Hits        53750    53750           
  Misses      30593    30593           

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