docker: Add Instruction Set Architectures to build matrix.

ci: Publish multi-arch images for both branch and tag refs.

Signed-off-by: Jason Volk <jason@zemos.net>

docker/Dockerfile.rocksdb

@@ -26,10 +26,10 @@ EOF
 
 FROM input AS rocksdb-build
 ARG rocksdb_shared=0
-ARG rocksdb_portable=1
+ARG rocksdb_portable="1"
 ARG rocksdb_opt_level="3"
 ARG rocksdb_build_type="Release"
-ARG rocksdb_cxx_flags="-ftls-model=initial-exec -mno-outline-atomics"
+ARG rocksdb_cxx_flags="-ftls-model=initial-exec"
 ARG rocksdb_make_verbose="ON"
 ARG rocksdb_make_rule_messages="OFF"
 ARG rocksdb_jemalloc=1