[clang][AST] Added assert to prevent infinite recursion in computing layout

While computing class layout, I met with infinite recursion. This
happened while executing user expression in lldb as record type was
incorrectly received from dwarf. This assert will replace the infinite
recursion with an error and will simplify further debugging of such cases.

Author: tgs-sc

clang/lib/AST/RecordLayoutBuilder.cpp

@@ -187,6 +187,7 @@ void EmptySubobjectMap::ComputeEmptySubobjectSizes() {
   // Check the bases.
   for (const CXXBaseSpecifier &Base : Class->bases()) {
     const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
+    assert(BaseDecl != Class && "Class cannot inherit from itself.");
 
     CharUnits EmptySize;
     const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);