[Support] FIx a warning

This patch fixes:

  llvm/include/llvm/Support/ErrorHandling.h:62:6: error: declaration
  is marked with '@deprecated' command but does not have a deprecation
  attribute [-Werror,-Wdocumentation-deprecated-sync]

Author: kazutakahirata

llvm/include/llvm/Support/Error.h

@@ -735,8 +735,8 @@ template <class T> class [[nodiscard]] Expected {
 #endif
 };
 
-/// @deprecated Use reportFatalInternalError() or reportFatalUsageError()
-/// instead.
+/// report_fatal_error below has been soft deprecated.
+/// Use reportFatalInternalError() or reportFatalUsageError() instead.
 [[noreturn]] void report_fatal_error(Error Err, bool gen_crash_diag = true);
 
 /// Report a fatal error that indicates a bug in LLVM.

llvm/include/llvm/Support/ErrorHandling.h

@@ -59,8 +59,8 @@ namespace llvm {
     ~ScopedFatalErrorHandler() { remove_fatal_error_handler(); }
   };
 
-/// @deprecated Use reportFatalInternalError() or reportFatalUsageError()
-/// instead.
+/// report_fatal_error below has been soft deprecated.
+/// Use reportFatalInternalError() or reportFatalUsageError() instead.
 [[noreturn]] void report_fatal_error(const char *reason,
                                      bool gen_crash_diag = true);
 [[noreturn]] void report_fatal_error(StringRef reason,