[compiler-rt] [AArch64][compiler-rt] Add memcpy, memset, memmove, memchr builtins. (PR #77496)

[Stephen Tozer via llvm-commits]

SLTozer wrote:

The above commit hasn't fully fixed the issue - the error has now changed from the original:
```
llvm-lit: /home/buildbot/buildbot-root/debug-iterators/llvm-project/llvm/utils/lit/lit/TestingConfig.py:152: fatal: unable to parse config file '/home/buildbot/buildbot-root/debug-iterators/build/runtimes/runtimes-bins/compiler-rt/unittests/lit.common.unit.configured', traceback: Traceback (most recent call last):
  File "/home/buildbot/buildbot-root/debug-iterators/llvm-project/llvm/utils/lit/lit/TestingConfig.py", line 140, in load_from_path
    exec(compile(data, path, "exec"), cfg_globals, None)
  File "/home/buildbot/buildbot-root/debug-iterators/build/runtimes/runtimes-bins/compiler-rt/unittests/lit.common.unit.configured", line 23
    config.aarch64_sme =
                        ^
SyntaxError: invalid syntax
```
To the new error:
```
llvm-lit: /home/buildbot/buildbot-root/debug-iterators/llvm-project/llvm/utils/lit/lit/TestingConfig.py:152: fatal: unable to parse config file '/home/buildbot/buildbot-root/debug-iterators/build/runtimes/runtimes-bins/compiler-rt/test/lit.common.configured', traceback: Traceback (most recent call last):
  File "/home/buildbot/buildbot-root/debug-iterators/llvm-project/llvm/utils/lit/lit/TestingConfig.py", line 140, in load_from_path
    exec(compile(data, path, "exec"), cfg_globals, None)
  File "/home/buildbot/buildbot-root/debug-iterators/build/runtimes/runtimes-bins/compiler-rt/test/lit.common.configured", line 66, in <module>
    set_default("aarch64_sme", )
TypeError: set_default() missing 1 required positional argument: 'value'
```


https://github.com/llvm/llvm-project/pull/77496