Rename wasm-delegations[-fields].h to def files (NFC) (#3941)

These files are special in that they use define symbols that are not
defined within those files or other files included in those files; they
are supposed to be defined in source files that include these headers.
This has caused clang-tidy to fail every time these files have changed
because they are not compilable per se.

This PR solves the problem by changing their extension to `def`, which
is also used in LLVM codebase. LLVM has dozens of files like this whose
extension is `def`, which makes these not checked by clang-tidy.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/ir/iteration.h b/src/ir/iteration.h
index a785fbc93..bfebf5a16 100644
--- a/src/ir/iteration.h
+++ b/src/ir/iteration.h
@@ -101,7 +101,7 @@ public:
 #define DELEGATE_FIELD_TYPE(id, name)
 #define DELEGATE_FIELD_ADDRESS(id, name)
 
-#include "wasm-delegations-fields.h"
+#include "wasm-delegations-fields.def"
   }
 
   Iterator begin() const { return Iterator(*this, 0); }