[clang] [flang] [flang][OpenMP] Upstream first part of `do concurrent` mapping (PR #126026)

[Damian Rouson via cfe-commits]

================
@@ -6910,6 +6910,10 @@ defm loop_versioning : BoolOptionWithoutMarshalling<"f", "version-loops-for-stri
 
 def fhermetic_module_files : Flag<["-"], "fhermetic-module-files">, Group<f_Group>,
   HelpText<"Emit hermetic module files (no nested USE association)">;
+
+def do_concurrent_parallel_EQ : Joined<["-"], "fdo-concurrent-parallel=">,
----------------
rouson wrote:

Great suggestion @clementval -- especially because there could someday be alternative options such as OpenACC for example. 

https://github.com/llvm/llvm-project/pull/126026