Update libc and activate align feature

src/liblibc

@@ -1 +1 @@
-Subproject commit b6d23ed45d72918239c0bfac11dc547895e59b81
+Subproject commit 6bdbf5dc937459bd10e6bc4dc52b0adbd8cf4358

src/rustc/libc_shim/Cargo.toml

@@ -36,4 +36,5 @@ compiler_builtins = { path = "../compiler_builtins_shim" }
 # Certain parts of libc are conditionally compiled differently than when used
 # outside rustc. See https://github.com/rust-lang/libc/search?l=Rust&q=stdbuild&type=&utf8=%E2%9C%93.
 stdbuild = []
-default = ["stdbuild"]
+default = ["stdbuild", "align"]
+align = []