Add STL checks via -D_GLIBCXX_ASSERTIONS in debug mode

[larroy]

Description

Add checks for C++ STL containers in DEBUG builds.

This important flag will check for correctness when using STL containers such as range checks and other situations that can cause out of bound errors and undefined behaviour while running in debug mode. It will make our code more resilient and help us catch bugs when running in Debug.

It doesn't affect release builds.

Checklist

Essentials

Please feel free to remove inapplicable items for your PR.

• The PR title starts with [MXNET-$JIRA_ID], where $JIRA_ID refers to the relevant JIRA issue created (except PRs with tiny changes)
• Changes are complete (i.e. I finished coding on this PR)
• All changes have test coverage:
• Unit tests are added for small changes to verify correctness (e.g. adding a new operator)
• Nightly tests are added for complicated/long-running ones (e.g. changing distributed kvstore)
• Build tests will be added for build configuration changes (e.g. adding a new build option with NCCL)
• Code is well-documented:
• For user-facing API changes, API doc string has been updated.
• For new C++ functions in header files, their functionalities and arguments are documented.
• For new examples, README.md is added to explain the what the example does, the source of the dataset, expected performance on test set and reference to the original paper if applicable
• Check the API doc at http://mxnet-ci-doc.s3-accelerate.dualstack.amazonaws.com/PR-$PR_ID/$BUILD_ID/index.html
• To the my best knowledge, examples are either not affected by this change, or have been fixed to be compatible with this change

[larroy]

@mxnet-label-bot add [Build,CMake,Make]

[larroy]

@mxnet-label-bot add [pr-awaiting-review]

[larroy]

@szha