Add a "fork" of musl as //fusl.

fusl/include/byteswap.h

Index: fusl/include/byteswap.h
diff --git a/fusl/include/byteswap.h b/fusl/include/byteswap.h
new file mode 100644
index 0000000000000000000000000000000000000000..00b9df3c9fa2b1511105ef60efca7650607a9f52
--- /dev/null
+++ b/fusl/include/byteswap.h
@@ -0,0 +1,26 @@
+#ifndef _BYTESWAP_H
+#define _BYTESWAP_H
+
+#include <features.h>
+#include <stdint.h>
+
+static __inline uint16_t __bswap_16(uint16_t __x)
+{
+	return __x<<8 | __x>>8;
+}
+
+static __inline uint32_t __bswap_32(uint32_t __x)
+{
+	return __x>>24 | __x>>8&0xff00 | __x<<8&0xff0000 | __x<<24;
+}
+
+static __inline uint64_t __bswap_64(uint64_t __x)
+{
+	return __bswap_32(__x)+0ULL<<32 | __bswap_32(__x>>32);
+}
+
+#define bswap_16(x) __bswap_16(x)
+#define bswap_32(x) __bswap_32(x)
+#define bswap_64(x) __bswap_64(x)
+
+#endif