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

fusl/src/string/memmove.c

Index: fusl/src/string/memmove.c
diff --git a/fusl/src/string/memmove.c b/fusl/src/string/memmove.c
new file mode 100644
index 0000000000000000000000000000000000000000..27f670e1a31fe860ff6ce17a453559ef42706aeb
--- /dev/null
+++ b/fusl/src/string/memmove.c
@@ -0,0 +1,36 @@
+#include <string.h>
+#include <stdint.h>
+
+#define WT size_t
+#define WS (sizeof(WT))
+
+void *memmove(void *dest, const void *src, size_t n)
+{
+	char *d = dest;
+	const char *s = src;
+
+	if (d==s) return d;
+	if (s+n <= d || d+n <= s) return memcpy(d, s, n);
+
+	if (d<s) {
+		if ((uintptr_t)s % WS == (uintptr_t)d % WS) {
+			while ((uintptr_t)d % WS) {
+				if (!n--) return dest;
+				*d++ = *s++;
+			}
+			for (; n>=WS; n-=WS, d+=WS, s+=WS) *(WT *)d = *(WT *)s;
+		}
+		for (; n; n--) *d++ = *s++;
+	} else {
+		if ((uintptr_t)s % WS == (uintptr_t)d % WS) {
+			while ((uintptr_t)(d+n) % WS) {
+				if (!n--) return dest;
+				d[n] = s[n];
+			}
+			while (n>=WS) n-=WS, *(WT *)(d+n) = *(WT *)(s+n);
+		}
+		while (n) n--, d[n] = s[n];
+	}
+
+	return dest;
+}