ci: use GCC 13 as cross compiler in dist-aarch64-linux

I'm proposing this GCC upgrade since it addresses bug #125619. The
regression in question affects stable release consumers who tend to have
no exposure to Rust build tools, so if at all possible, I would like to
have it resolved in the next stable release. I have tried to fix the bug
in `compiler-builtins`, which led to submitting a PR for `compiler-rt`
in upstream LLVM, but it may take a long time before these upstreams
address this regression.

A summary of why upgrading GCC solves the regression follows.
`__multc3()` is a builtin function `compiler-builtins` exposes for
specifically aarch64, non-Windows targets [1]. The object file for it is
included in `staticlib` archives through `libstd`. The implementation
for `__multc3()` is from `multc3.c`, part of LLVM's `compiler-rt`.
Upstream `compiler-rt` normally builds the C file using the Clang
from the same LLVM version. On the other hand, `compiler-builtins`
builds the C file using GCC, outside of the usual LLVM build system.
The upstream implementation doesn't have feature detection which
works for GCC version older than 10, and ends up producing an
unlinkable object.

Upstream LLVM might be slow to respond to this issue as they might deem
`compiler-builtin` as doing something out of the ordinary from their
perspective. They might reasonably assume everyone builds `compiler-rt`
through LLVM's build system.

I have done the following to test this change:
 - verified that a local build without this patch exhibits the
   regression.
 - verified that with this patch, the object for `__multc3()` has no
   reference to undefined functions in the symbol table.
 - verified that with this patch, `rustc` is usable to build Ruby with
   YJIT, and that the reported regression is resolved.

[1]: https://github.com/rust-lang/compiler-builtins/blob/c04eb9e1afb72bdf943f5e5d77b3812f40526602/build.rs#L524-L539

src/ci/docker/README.md

@@ -233,7 +233,7 @@ For targets: `aarch64-unknown-linux-gnu`
 - Operating System > Linux kernel version = 4.1.49
 - Binary utilities > Version of binutils = 2.29.1
 - C-library > glibc version = 2.17 -- aarch64 support was introduced in this version
-- C compiler > gcc version = 8.5.0
+- C compiler > gcc version = 13.2.0
 - C compiler > C++ = ENABLE -- to cross compile LLVM
 
 ### `i586-linux-gnu.defconfig`

src/ci/docker/host-x86_64/dist-aarch64-linux/aarch64-linux-gnu.defconfig

@@ -6,7 +6,5 @@ CT_ARCH_ARM=y
 CT_ARCH_64=y
 CT_KERNEL_LINUX=y
 CT_LINUX_V_4_1=y
-CT_BINUTILS_V_2_29=y
 CT_GLIBC_V_2_17=y
-CT_GCC_V_8=y
 CT_CC_LANG_CXX=y