Auto merge of #155710 - tgross35:rollup-skXlTFI, r=tgross35

Rollup of 7 pull requests

Successful merges:

 - rust-lang/rust#155660 (c-variadic: fix for sparc64)
 - rust-lang/rust#153482 (tests/ui/macros: add annotations for reference rules)
 - rust-lang/rust#155075 (Add docs about SDKs and C compilation on armv7a-vex-v5)
 - rust-lang/rust#155685 (Fix `get_child_at_index` return type hints)
 - rust-lang/rust#155686 (Fix array template arg lookup behavior)
 - rust-lang/rust#155689 (Const initialize `LOCK_LATCH` thread local)
 - rust-lang/rust#155690 (Fix classify_union to return Union for regular unions)

Author: bors