GitLab

- See commit 54102b7c2f1b8cd7430d36f7599ba2ab9dfa8607

This ensures that the linker will throw a build error in the event that the stack size can not be provided.

A new bios command "stack" now exists to print the total and free stack sizes.
The system also checks the stack usage after any console command and immediately
before boot. If a stack overflow is detected, and error is reported.

- Add a dummy memory barrier in flush_cpu_dcache to work around an issue with clang-format.

This update enables access to the on-board FPGA Flash device
via a second Tercel SPI controller.

- Don't exclude all files when a parent directory is named build.
- Don't exclude .gitignore and related files, only exclude .git folders

This updates the jenkins configuration to match the recommendations from
https://github.com/jenkinsci/gitlab-plugin