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

fusl/src/misc/a64l.c

+#include <stdlib.h>
+#include <string.h>
+#include <stdint.h>
+
+static const char digits[] =
+        "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
+
+long a64l(const char *s)
+{
+        int e;
+        uint32_t x = 0;
+        for (e=0; e<36 && *s; e+=6, s++)
+                x |= (strchr(digits, *s)-digits)<<e;
+        return x;
+}
+
+char *l64a(long x0)
+{
+        static char s[7];
+        char *p;
+        uint32_t x = x0;
+        for (p=s; x; p++, x>>=6)
+                *p = digits[x&63];
+        *p = 0;
+        return s;
+}