AST: honour throws in AccessorDecl::createImplicit

We would previously unconditionally create the accessor as a throwing
accessor irrespective of the parameter. This seems like an oversight and
results in an incorrect accessor being formed. This was caught while
trying to improve the ClangImporter's handling of aliasing macros.

Author: compnerd

lib/AST/Decl.cpp

@@ -11102,7 +11102,7 @@ AccessorDecl *AccessorDecl::createImplicit(ASTContext &ctx,
       ctx, /*declLoc=*/SourceLoc(),
       /*accessorKeywordLoc=*/SourceLoc(), accessorKind,
       storage, async, /*asyncLoc=*/SourceLoc(),
-      /*throws=*/true, /*throwsLoc=*/SourceLoc(),
+      /*throws=*/throws, /*throwsLoc=*/SourceLoc(),
       thrownType, parent,
       /*clangNode=*/ClangNode());
   D->setImplicit();