Update core_io submodule to a valid commit.

5 jobs for update_toolchain in 2 minutes and 19 seconds
Status Job ID Name Coverage
  Build
failed #32944
build:linux

00:02:19

failed #32945
build:redox

00:01:31

 
  Test
failed #32948
fmt

00:01:26

skipped #32946
test:linux
skipped #32947
allowed to fail
test:redox
 
Name Stage Failure
failed
build:linux Build
make: *** Waiting for unfinished jobs....
make: *** [Makefile:178: "target/x86_64-unknown-linux-gnu"/release/crt0.o] Error 101
make: *** [Makefile:186: "target/x86_64-unknown-linux-gnu"/release/crtn.o] Error 101
make: *** [Makefile:190: "target/x86_64-unknown-linux-gnu"/release/ld_so.o] Error 101
error: "/root/.rustup/toolchains/nightly-2021-03-15-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/Cargo.lock" does not exist, unable to build with the standard library, try:
rustup component add rust-src
make: *** [Makefile:173: "target/x86_64-unknown-linux-gnu"/release/librelibc.a] Error 101
Cleaning up file based variables
ERROR: Job failed: exit code 1
failed
build:redox Build
        rustup component add rust-src

make: *** [Makefile:178: "target/x86_64-unknown-redox"/release/crt0.o] Error 101
make: *** [Makefile:186: "target/x86_64-unknown-redox"/release/crtn.o] Error 101
error: "/root/.redoxer/toolchain/lib/rustlib/src/rust/Cargo.lock" does not exist, unable to build with the standard library, try:
rustup component add rust-src
make: *** [Makefile:173: "target/x86_64-unknown-redox"/release/librelibc.a] Error 101
Cleaning up file based variables
ERROR: Job failed: exit code 1
failed
fmt Test
+    //fn dlrealloc(oldmem: *mut c_void, bytes: size_t) -> *mut c_void;
+ //fn dlfree(mem: *mut c_void);
}

pub struct Allocator {
Warning: Unknown configuration option `fn_args_density`
Warning: the `merge_imports` option is deprecated. Use `imports_granularity=Crate` instead
Cleaning up file based variables
ERROR: Job failed: exit code 1