crc32: Buffer up log output to avoid prefix-chunking, fix func

[ALTracer]

Detailed description

• This is a fix to one of my edited/contributed features regarding compare-sections via qCRC.
• There are three existing problems, which are not critical to upstream BMD here.
• This PR updates crc32 dispatch code to deal with them.

1. Because of Fix: Replace attribute alias in CRC32 #1713 and requirements to support Windows and MacOS (cross-platform portable software), the __func__ portion of log became identical as collateral damage. This change restores the behaviour intended in Fix: qCRC performance uplift #1708, so that we can tell apart speed reports from BMF+ENABLE_DEBUG and BMDA.
2. On out-of-tree platforms like Farpatch which use BMD as a git submodule directly, custom logger implementations format every DEBUG_INFO() call etc. by prepending loglevel and timestamp, so the 2-3 piece logmessage gets broken and mixed. This change buffers the optional output pieces into a zeroed stack buffer via snprintf() to avoid that.
3. Xtensa Farpatch crashes on every divide-by-zero, which can happen here when <1 milliseconds are reported elapsed by corresponding platform timing code. BMF on Cortex-M3 does not trap integer divide-by-zero into UsageFault, so it was never affected. BMDA usually gets more than 1ms due to USB FS delays and all the layer overheads. This change skips the speed report by checking for both length and time to be big enough.

Your checklist for this pull request

• I've read the Code of Conduct
• I've read the guidelines for contributing to this repository
• It builds for hardware native (see Building the firmware)
• It builds as BMDA (see Building the BMDA)
• I've tested it to the best of my ability
• My commit messages provide a useful short description of what the commits do

Closing issues

Fixes some issues in Farpatch.

[xobs]

I like this change! It improves readability when doing checksum benchmarking.

[dragonmux]

Please could you rebase this on main and we'll look at getting this reviewed as soon as we can.

[dragonmux]

Couple of notes in doing a review - but with them fixed, this looks basically ready to merge. Good job!

[dragonmux]

This LGTM, merging. Thank you for the contribution!

While there's a known issue with 64-bit targets here, we're not going to have this block merging this as that's a separate issue that'll take a pile more work to fix and so should be a separate PR.