feat: implement merge sort for jCC lists to ensure chronological dump…

[not-matthias]

… order

[Copilot]

Pull Request Overview

This PR adds chronological ordering to jump call cost center (jCC) dump output by tracking creation sequence numbers. The change ensures jCC entries are dumped in the order they were created rather than in an arbitrary order determined by the linked list structure.

• Added a global counter to track jCC creation sequence
• Implemented merge sort algorithm for jCC linked lists
• Applied sorting to jCC lists before dumping to ensure chronological order

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
callgrind/jumps.c	Added global jcc_creation_counter and initialization of creation_seq field during jCC creation
callgrind/global.h	Added creation_seq field to jCC structure for tracking creation order
callgrind/dump.c	Implemented merge sort for jCC lists and applied sorting before dumping jCC data

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[GuillaumeLagrange]

olgtm, but let's wait for #4 before merging this IMO, it's both more prio and includes performance measurement so we'll be able to measure the impact of this

[art049]

lgtm overall but can you rebase this on the bench PR? we need to make sure this won't affect performance in most cases

[codspeed-hq]

CodSpeed Performance Report

Merging #3 will degrade performances by 49.54%

_{Comparing cod-578-fix-span-ordering-on-the-flamegraph (e8fd6f3) with cod-1573-v431-seems-to-cause-hangs (77811f8)}

Summary

❌ 2 regressions
✅ 66 untouched

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
❌	test_valgrind[valgrind-3.25.1.codspeed, python3 testdata/test.py, full-no-inline]	5.3 s	6.2 s	-15.4%
❌	test_valgrind[valgrind-3.26.0, testdata/take_strings-aarch64 varbinview_non_null, full-with-inline]	7.1 s	14.1 s	-49.54%