Merge changes from develop in preparation of the 0.3.29 release

Update the Changelog for version 0.3.29

Replace LAPACK ?LARFT with a recursive implementation (Reference-LAPACK PR 1080)

Remove comparison that is always false (Reference-LAPACK PR 1062)

Replace while loop in generic C/ZGEMM_BETA to avoid going out of bounds

Optimize the omatcopy_cn/zomatcopy_cn kernels with RVV 1.0 intrinsic.

Add the test cases of rot to improve the unit tests for rot_rvv.

LoongArch64: Update symv

Do not check LDVT in LAPACKE_?gesvd_work if VT is not used anyway

Cirrus CI: Update FreeBSD jobs to 14.1

Signed-off-by: tingbo.liao <tingbo.liao@starfivetech.com>

remove fastmath from x280 target

Update Makefile.riscv64

remove fast-math

Rewrite the "Build system" documentation page

PPC970: fix scal

Content is reviewed fairly carefully, and should be up to the
same standard as the rest of the docs now.

Uses Mermaid to render it as a diagram in the html docs.

The doc build is now clean of warnings again.

This only fixes Markdown syntax, and adds a few headers to bring
some structure into the long list of variables that influence the
build. It does not add or remove variables.

Add a documentation page for the runtime variables

This reverts commit 9b9c0aa5c9.

Add build instructions for Huawei's HarmonyOS to the documentation