[clang] Mark some language options as benign.

I'm  fairly certain that the options in this CL are benign, as I don't believe they affect the AST.
* RTTI - shouldn't affect the AST, should only affect codegen
* Trivial var init - also should only affect codegen
* Stack protector - also codegen
* Exceptions - Since exceptions do allow new things in the AST, but I'm pretty sure that they can differ in parent and child safely, I marked it as compatible instead.

I welcome any input from someone more familiar with this than me, as I might be wrong.

Author: matts1

clang/docs/ReleaseNotes.rst

@@ -471,6 +471,7 @@ Bug Fixes to C++ Support
 - Clang now issues an error when placement new is used to modify a const-qualified variable
   in a ``constexpr`` function. (#GH131432)
 - Clang now emits a warning when class template argument deduction for alias templates is used in C++17. (#GH133806)
+- Clang modules now allow a module and its user to have a larger variety of configurations.
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^

clang/include/clang/Basic/LangOptions.def

@@ -398,11 +398,11 @@ BENIGN_LANGOPT(HalfNoSemanticInterposition, 1, 0,
                "Like -fno-semantic-interposition but don't use local aliases")
 ENUM_LANGOPT(StackProtector, StackProtectorMode, 2, SSPOff,
              "stack protector mode")
-ENUM_LANGOPT(TrivialAutoVarInit, TrivialAutoVarInitKind, 2, TrivialAutoVarInitKind::Uninitialized,
+BENIGN_ENUM_LANGOPT(TrivialAutoVarInit, TrivialAutoVarInitKind, 2, TrivialAutoVarInitKind::Uninitialized,
              "trivial automatic variable initialization")
-VALUE_LANGOPT(TrivialAutoVarInitStopAfter, 32, 0,
+BENIGN_VALUE_LANGOPT(TrivialAutoVarInitStopAfter, 32, 0,
              "stop trivial automatic variable initialization after the specified number of instances. Must be greater than 0.")
-VALUE_LANGOPT(TrivialAutoVarInitMaxSize, 32, 0,
+BENIGN_VALUE_LANGOPT(TrivialAutoVarInitMaxSize, 32, 0,
              "stop trivial automatic variable initialization if var size exceeds the specified size (in bytes). Must be greater than 0.")
 ENUM_LANGOPT(SignedOverflowBehavior, SignedOverflowBehaviorTy, 2, SOB_Undefined,
              "signed integer overflow handling")