[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

@@ -562,7 +562,7 @@ Bug Fixes in This Version
 - Fixed a bug where an attribute before a ``pragma clang attribute`` or
   ``pragma clang __debug`` would cause an assertion. Instead, this now diagnoses
   the invalid attribute location appropriately. (#GH137861)
-- Fixed a crash when a malformed ``_Pragma`` directive appears as part of an 
+- Fixed a crash when a malformed ``_Pragma`` directive appears as part of an
   ``#include`` directive. (#GH138094)
 
 Bug Fixes to Compiler Builtins
@@ -674,6 +674,7 @@ Bug Fixes to C++ Support
   whose type depends on itself. (#GH51347), (#GH55872)
 - Improved parser recovery of invalid requirement expressions. In turn, this
   fixes crashes from follow-on processing of the invalid requirement. (#GH138820)
+- Clang modules now allow a module and its user to differ on TrivialAutoVarInit*
 
 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")