[clang] [C23] Fix crash with _BitInt running clang-tidy

This crash was exposed recently in our randomized testing. _BitInts were
not being handled properly during IntegerLiteral visitation. This patch
addresses the problem for now.

The BitIntType has no getKind() method, so the FoldingSetID is taken
from the APInt value representing the _BitInt(), similar to other
methods in StmtProfile.cpp. Seems also the const qualifier was missing
on the nonstatic profile method of the BitIntType class.

Crash seen (summary form):

clang-tidy: <src-root>/llvm/include/llvm/Support/Casting.h:566:
decltype(auto) llvm::cast(const From&) [with To = clang::BuiltinType;
From = clang::QualType]: Assertion `isa<To>(Val) && "cast<Ty>() argument
of incompatible type!"' failed

...
  #9 <address> decltype(auto) llvm::cast<clang::BuiltinType,
       clang::QualType>(clang::QualType const&)
       <src-root>/llvm/include/llvm/Support/Casting.h:566:3
 #10 <address> clang::BuiltinType const* clang::Type::castAs<clang::BuiltinType>() const
       <bin-root>/tools/clang/include/clang/AST/TypeNodes.inc:86:1
 #11 <address> (anonymous namespace)::StmtProfiler::VisitIntegerLiteral(
       clang::IntegerLiteral const*)
       <src-root>/clang/lib/AST/StmtProfile.cpp:1362:64
 #12 <address> clang::StmtVisitorBase<llvm::make_const_ptr,
       (anonymous namespace)::StmtProfiler, void>::Visit(clang::Stmt const*)
       <src-root>/clang/include/clang/AST/StmtNodes.inc:1225:1
...

Reviewed By: donat.nagy

clang-tools-extra/test/clang-tidy/checkers/bugprone/inc-dec-in-conditions-bitint-no-crash.c

@@ -0,0 +1,9 @@
+// RUN: %check_clang_tidy %s bugprone-inc-dec-in-conditions %t
+
+_BitInt(8) v_401_0() {
+  0 && ({
+    _BitInt(5) y = 0;
+    16777215wb ?: ++y;
+  });
+}
+// CHECK-MESSAGES: warning 

clang/include/clang/AST/Type.h

@@ -6642,7 +6642,7 @@ class BitIntType final : public Type, public llvm::FoldingSetNode {
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
-  void Profile(llvm::FoldingSetNodeID &ID) {
+  void Profile(llvm::FoldingSetNodeID &ID) const {
     Profile(ID, isUnsigned(), getNumBits());
   }
 

clang/lib/AST/StmtProfile.cpp

@@ -1333,7 +1333,13 @@ void StmtProfiler::VisitPredefinedExpr(const PredefinedExpr *S) {
 void StmtProfiler::VisitIntegerLiteral(const IntegerLiteral *S) {
   VisitExpr(S);
   S->getValue().Profile(ID);
-  ID.AddInteger(S->getType()->castAs<BuiltinType>()->getKind());
+
+  QualType T = S->getType();
+  ID.AddInteger(T->getTypeClass());
+  if (auto BitIntT = T->getAs<BitIntType>())
+    BitIntT->Profile(ID);
+  else
+    ID.AddInteger(T->castAs<BuiltinType>()->getKind());
 }
 
 void StmtProfiler::VisitFixedPointLiteral(const FixedPointLiteral *S) {