Remove using util.h in various headers in favor of util-types.h

src/Overflow.h

@@ -2,9 +2,14 @@
 
 #pragma once
 
-#include "zeek/Type.h"
+#include "zeek/util-types.h"
 
-namespace zeek::detail {
+namespace zeek {
+
+class Type;
+class Val;
+
+namespace detail {
 
 inline bool double_to_count_would_overflow(double v) { return v < 0.0 || v > static_cast<double>(UINT64_MAX); }
 
@@ -18,4 +23,5 @@ inline bool count_to_int_would_overflow(zeek_uint_t v) { return v > INT64_MAX; }
 
 extern bool would_overflow(const zeek::Type* from_type, const zeek::Type* to_type, const Val* val);
 
-} // namespace zeek::detail
+} // namespace detail
+} // namespace zeek