- replace `--parallel <n>` and `-j<n>` for individual commands with
`MAKEFLAGS`, for jobs not yet doing it.
This enables parallel builds in distcheck / maketgz-and-verify-in-tree,
where `-j` option was missing.
- add `--parallel` for iOS Xcode job for improved performance.
- drop redundant `-j5` for Android jobs.
- drop stray `cmake --config` options from single-target jobs (cygwin,
msys/mingw, dl-mingw, non-native). Drop redundant
`CMAKE_RUNTIME_OUTPUT_DIRECTORY_*` settings too.
- GHA/windows: add timeout for package install steps where missing.
- GHA/non-native: specify target type explicitly for iOS cmake jobs.
Xcode default was already Debug, single-target default was generic,
now it's Release, with unity batch to keep it fast.
`MAKEFLAGS` is necessary for autotools jobs and CMake jobs using
the default (GNU Make) generator. It's ignored by Ninja and other tools.
`cmake --parallel` is still necessary for jobs with Visual Studio or
Xcode generators. Parallelism is 5 for GHA Linux and Windows runners,
4 for macOS, 3 for VMs, 2 for AppVeyor.
Closes#16502
08a29e7f18