Rollup merge of rust-lang#148886 - ZhongyaoChen:promote-riscv64a23-to-tier2, r=Mark-Simulacrum

Add riscv64a23-unknown-linux-gnu to build-manifest TARGETS

This enables rustup distribution of the rust-std component for the riscv64a23-unknown-linux-gnu target
(Previous PR rust-lang#148435 missed this step.)

Author: Zalathar

src/tools/build-manifest/src/main.rs

@@ -153,6 +153,7 @@ static TARGETS: &[&str] = &[
     "riscv32imafc-unknown-none-elf",
     "riscv32gc-unknown-linux-gnu",
     "riscv64imac-unknown-none-elf",
+    "riscv64a23-unknown-linux-gnu",
     "riscv64gc-unknown-hermit",
     "riscv64gc-unknown-none-elf",
     "riscv64gc-unknown-linux-gnu",