[llvm] [llvm] Use ISO C90 style comment in C code (PR #128192)

[via llvm-commits]

https://github.com/foxtran created https://github.com/llvm/llvm-project/pull/128192

This patch fixes warning which occurs during compilation of clang with GCC:
```
C++ style comments are not allowed in ISO C90
```

Similar PR for clang: #128189 

>From 9848ba238611a9215a985055043656227a322031 Mon Sep 17 00:00:00 2001
From: "Igor S. Gerasimov" <i.s.ger at ya.ru>
Date: Fri, 21 Feb 2025 17:04:19 +0100
Subject: [PATCH] Use ISO C90 style comment in C code

---
 llvm/include/llvm/Support/AutoConvert.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/llvm/include/llvm/Support/AutoConvert.h b/llvm/include/llvm/Support/AutoConvert.h
index 5d6d9394ef1d8..4f6a3d2ac48fa 100644
--- a/llvm/include/llvm/Support/AutoConvert.h
+++ b/llvm/include/llvm/Support/AutoConvert.h
@@ -55,14 +55,14 @@ std::error_code restorezOSStdHandleAutoConversion(int FD);
 /** \brief Set the tag information for a file descriptor. */
 std::error_code setzOSFileTag(int FD, int CCSID, bool Text);
 
-// Get the the tag ccsid for a file name or a file descriptor.
+/** Get the the tag ccsid for a file name or a file descriptor. */
 ErrorOr<__ccsid_t> getzOSFileTag(const char *FileName, const int FD = -1);
 
-// Query the file tag to determine if it needs conversion to UTF-8 codepage.
+/** Query the file tag to determine if it needs conversion to UTF-8 codepage. */
 ErrorOr<bool> needzOSConversion(const char *FileName, const int FD = -1);
 
-} // namespace llvm
-#endif // __cplusplus
+} /* namespace llvm */
+#endif /* __cplusplus */
 
 #endif /* __MVS__ */