[singlejar] Use gcc-style attr_packed for Clang on Windows
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#include <string>
#include <type_traits>
-#ifdef _MSC_VER
+#if defined(_MSC_VER) && !defined(__clang__)
#pragma pack(push, 1)
#define attr_packed
#else
@@ -653,7 +653,7 @@ class ECD64 {
} attr_packed;
static_assert(56 == sizeof(ECD64), "ECD64 class fields layout is incorrect.");
-#ifdef _MSC_VER
+#if defined(_MSC_VER) && !defined(__clang__)
#pragma pack(pop)
#endif
