[clang] [llvm] [SystemZ][z/OS] Open text files as text (PR #228189)

[via llvm-commits]

sujianIBM wrote:

I may understand this wrong, but is this change safe when the Mips/X86 test is run on other host OS?
I see `MemoryBuffer::getFile()` calls `getFileAux()` which has
```
  Expected<sys::fs::file_t> FDOrErr = sys::fs::openNativeFileForRead(
      Filename, IsText ? sys::fs::OF_TextWithCRLF : sys::fs::OF_None);
```
and `sys::fs::OF_TextWithCRLF` means "in text mode with Windows-style line endings (\r\n)."
Thanks!

https://github.com/llvm/llvm-project/pull/228189