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

fusl/src/string/strlen.c

Index: fusl/src/string/strlen.c
diff --git a/fusl/src/string/strlen.c b/fusl/src/string/strlen.c
new file mode 100644
index 0000000000000000000000000000000000000000..929ddcbc1c2594762c7b44cdfd5edf0f2955d1f6
--- /dev/null
+++ b/fusl/src/string/strlen.c
@@ -0,0 +1,18 @@
+#include <string.h>
+#include <stdint.h>
+#include <limits.h>
+
+#define ALIGN (sizeof(size_t))
+#define ONES ((size_t)-1/UCHAR_MAX)
+#define HIGHS (ONES * (UCHAR_MAX/2+1))
+#define HASZERO(x) ((x)-ONES & ~(x) & HIGHS)
+
+size_t strlen(const char *s)
+{
+	const char *a = s;
+	const size_t *w;
+	for (; (uintptr_t)s % ALIGN; s++) if (!*s) return s-a;
+	for (w = (const void *)s; !HASZERO(*w); w++);
+	for (s = (const void *)w; *s; s++);
+	return s-a;
+}