Temporarily disable Dragonfly in CI. (#1035)

* Temporarily disable Dragonfly in CI.

Dragonfly builds are failing in CI; so temporarily disable them.

* Re-disable armv6k-nintendo-3ds in CI.

.github/workflows/main.yml

@@ -208,7 +208,8 @@ jobs:
     - run: rustup component add rust-src
     - run: cargo check -Z build-std --target x86_64-unknown-openbsd --all-targets --features=all-apis
     - run: cargo check -Z build-std --target mips64-openwrt-linux-musl --all-targets --features=all-apis
-    - run: cargo check -Z build-std --target x86_64-unknown-dragonfly --all-targets --features=all-apis
+    # Temporarily disable this because the target appears to have breakage on nightly.
+    # - run: cargo check -Z build-std --target x86_64-unknown-dragonfly --all-targets --features=all-apis
     - run: cargo check -Z build-std --target sparc-unknown-linux-gnu --all-targets --features=all-apis
     # Temporarily disable this because the target appears to have changed and needs
     # fixes and we transitively dev-depend on what can be an older version of rustix.
@@ -223,7 +224,8 @@ jobs:
     - run: cargo check -Z build-std --target=aarch64-unknown-nto-qnx710 --features=all-apis
     - run: cargo check -Z build-std --target=x86_64-pc-nto-qnx710 --features=all-apis
     # Temporarily disable --features=all-apis, which doesn't build yet.
-    - run: cargo check -Z build-std --target=armv6k-nintendo-3ds
+    # Temporarily disable this because the target appears to have breakage on nightly.
+    #- run: cargo check -Z build-std --target=armv6k-nintendo-3ds
     # Temporarily disable armv7-sony-vita-newlibeabihf due to std using SOMAXCONN.
     #- run: cargo check -Z build-std --target=armv7-sony-vita-newlibeabihf --features=all-apis
     # `std` doesn't appear to build on AIX yet, so test in `no_std` mode.