fix: Add missing endian conversion macros to enable MacOS builds

We had been manually hacking this into our headers to build locally. I _believe_ this is the correct place to put them, or at least this change allows Gazette to build on my Mac without hacks.

consumer/store-sqlite/store.cpp

@@ -6,6 +6,27 @@
 #include <rocksdb/db.h>
 #include <rocksdb/utilities/write_batch_with_index.h>
 
+#ifdef __APPLE__
+
+#include <libkern/OSByteOrder.h>
+
+#define htobe16(x) OSSwapHostToBigInt16(x)
+#define htole16(x) OSSwapHostToLittleInt16(x)
+#define be16toh(x) OSSwapBigToHostInt16(x)
+#define le16toh(x) OSSwapLittleToHostInt16(x)
+
+#define htobe32(x) OSSwapHostToBigInt32(x)
+#define htole32(x) OSSwapHostToLittleInt32(x)
+#define be32toh(x) OSSwapBigToHostInt32(x)
+#define le32toh(x) OSSwapLittleToHostInt32(x)
+
+#define htobe64(x) OSSwapHostToBigInt64(x)
+#define htole64(x) OSSwapHostToLittleInt64(x)
+#define be64toh(x) OSSwapBigToHostInt64(x)
+#define le64toh(x) OSSwapLittleToHostInt64(x)
+
+#endif
+
 // recFS is a sqlite3_vfs which records mutations of stateful SQLite DB files.
 struct recFS {
   sqlite3_vfs base;      // C-style subclass (is-a sqlite3_vfs).