multi-arch.yml and linuxkm.yml were installing apt packages with inline
shell commands. Replace them with the install-apt-deps composite action
for consistent retry behavior and caching.
* add "-Wnull-dereference" to all existing "-pedantic -Wdeclaration-after-statement" configs;
* add an --enable-sp-math config to .github/workflows/pq-all.yml and .github/workflows/multi-arch.yml.
.github/workflows: update async.yml, multi-arch.yml, multi-compiler.yml, no-malloc.yml, opensslcoexist.yml, and os-check.yml, with -pedantic and related flags, and add --enable-riscv-asm to multi-arch.yml RISC-V scenario;
configure.ac: clarify error message for "SP ASM not available for CPU."
Juliusz Sosinowicz
Daniel Pouzzner
Sean Parkinson
Andras Fekete
Marco Oliverio
gojimmypi
res0nance