[clang] [clang] Add deprecation warning for `-Ofast` driver option (PR #98736)

[Sebastian Pop via cfe-commits]

================
@@ -442,6 +442,10 @@ def warn_drv_deprecated_arg : Warning<
 def warn_drv_deprecated_arg_no_relaxed_template_template_args : Warning<
   "argument '-fno-relaxed-template-template-args' is deprecated">,
   InGroup<DeprecatedNoRelaxedTemplateTemplateArgs>;
+def warn_drv_deprecated_arg_ofast : Warning<
+  "argument '-Ofast' is deprecated; use '-O3 -ffast math' for the same behavior,"
----------------
sebpop wrote:

Missing dash between ffast and math. 
Here and several times below.

https://github.com/llvm/llvm-project/pull/98736