Skipping arm64 for lack of toolchain on the bots.
Disable tcmalloc on arm, where it fails to compile.
The builds are split into separate steps instead of using a shorter invocation like `--mode=debug,release --arch=ia32,x64,arm,riscv64` to avoid per-step timeouts.
Change-Id: Iccf5e6e8d91584147138ac37487560a7cc608b6f
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/283121
Reviewed-by: Siva Annamalai <asiva@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Ryan Macnak
badd96032d