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

fusl/arch/arm/src/__aeabi_memmove.c

Index: fusl/arch/arm/src/__aeabi_memmove.c
diff --git a/fusl/arch/arm/src/__aeabi_memmove.c b/fusl/arch/arm/src/__aeabi_memmove.c
new file mode 100644
index 0000000000000000000000000000000000000000..951e7d3952e3f6527af0d75294496c6786877061
--- /dev/null
+++ b/fusl/arch/arm/src/__aeabi_memmove.c
@@ -0,0 +1,9 @@
+#include <string.h>
+#include "libc.h"
+
+void __aeabi_memmove(void *dest, const void *src, size_t n)
+{
+	memmove(dest, src, n);
+}
+weak_alias(__aeabi_memmove, __aeabi_memmove4);
+weak_alias(__aeabi_memmove, __aeabi_memmove8);