Update stdarch submodule Updates the stdarch submodule. ## Merged PRs - rust-lang/stdarch#1797 - rust-lang/stdarch#1758 - rust-lang/stdarch#1798 - rust-lang/stdarch#1811 - rust-lang/stdarch#1810 - rust-lang/stdarch#1807 - rust-lang/stdarch#1806 - rust-lang/stdarch#1812 - rust-lang/stdarch#1795 - rust-lang/stdarch#1796 - rust-lang/stdarch#1813 - rust-lang/stdarch#1816 - rust-lang/stdarch#1818 - rust-lang/stdarch#1820 - rust-lang/stdarch#1819 r? `@Amanieu` `@rustbot` label T-libs-api Closes rust-lang/rust#111137