[clang] [llvm] [SystemZ][z/OS] Refactor AutoConvert.h to remove large MVS guard (PR #143174)

[Sean Perry via llvm-commits]

================
@@ -11,30 +11,37 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifdef __MVS__
----------------
perry-ca wrote:

See my previous comment.  If we write the interface in AutoConvert.h so the functions are inline functions that do nothing for non-z/OS and then call these functions for z/OS, we can keep this file are z/OS only and not have function calls that return right away. 

https://github.com/llvm/llvm-project/pull/143174