* Replace OQS_PORTABLE_BUILD with OQS_DIST_BUILD
Also introduces OQS_OPT_TARGET and removes OQS_USE_CPU_EXTENSIONS
* Only compile sha3 avx2 code on Linux|Darwin
* Use new ARCH_ARM[X] flags in SIKE CMakeLists
* Update test_portability and rename to test_distbuild
* Update documentation for building Windows AMD64 from Ubuntu Bionic
* Update scripts/build-android.sh
* More specific CMAKE_SYSTEM_PROCESSOR for rasppi toolchain
* CI: Use OQS_DIST_BUILD in some jobs
* Replace OQS_get_available_CPU_extensions by OQS_CPU_has_extension
* ARM64v8/ARM32v7 runtime cpu feature detection
* Compile-time detection of some ARM features
* Toolchain files to cross compile for ARM32v7 and ARM64v8
* Remove unnecessary references to CMAKE_BUILD_TYPE=Release
* Use OQS_DIST_BUILD=ON on Windows
* Fix OQS_PORTABLE_BUILD logic for schemes imported with copy_from_upstream
* Correct interpretation of pclmulqdq required flag
* Only run detect_gcc_clang_intrinsics on X86_64
* Point Kyber and Dilithium to pqcrystals-repo.
* Pulls Kyber and Dilithium from PQCrystals using copy_from_upstream
* Dilithium Round 3
* Kyber round 3
* Updates Dilithium Round 3 KAT
* Updates kyber.md and dilithium.md (manual changes after running copy_from_upstream)
* Update copy_from_pqclean / copy_from_upstream (#880)
* Renames copy_from_pqclean to copy_from_upstream.
* Adds 'upstreams' field to copy_from_upstream.yml, allowing to specify upstream repositories, branches and commits.
* Modifies "copy" command in copy_from_upstream: sources are pulled from specified git-repositories. Implementation folders in $LIBOQS_DIR/src will be prefixed with the upstream-name.
* Adds "verify" command in copy_from_upstream: Implementations in $LIBOQS_DIR/src are compared with expected upstream versions.
* Prepares for copying pqclean, pqcrystals-kyber and pqcrystals-dilithium from upstream.
* Updates copy_from_upstream to process common dependencies from an upstream.
* Adds reminder text to manually update algorithm docs .md files after copying
