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

fusl/src/stdlib/strtod.c

+#include <stdlib.h>
+#include "shgetc.h"
+#include "floatscan.h"
+#include "stdio_impl.h"
+#include "libc.h"
+
+static long double strtox(const char *s, char **p, int prec)
+{
+        FILE f = {
+                .buf = (void *)s, .rpos = (void *)s,
+                .rend = (void *)-1, .lock = -1
+        };
+        shlim(&f, 0);
+        long double y = __floatscan(&f, prec, 1);
+        off_t cnt = shcnt(&f);
+        if (p) *p = cnt ? (char *)s + cnt : (char *)s;
+        return y;
+}
+
+float strtof(const char *restrict s, char **restrict p)
+{
+        return strtox(s, p, 0);
+}
+
+double strtod(const char *restrict s, char **restrict p)
+{
+        return strtox(s, p, 1);
+}
+
+long double strtold(const char *restrict s, char **restrict p)
+{
+        return strtox(s, p, 2);
+}
+
+weak_alias(strtof, strtof_l);
+weak_alias(strtod, strtod_l);
+weak_alias(strtold, strtold_l);
+weak_alias(strtof, __strtof_l);
+weak_alias(strtod, __strtod_l);
+weak_alias(strtold, __strtold_l);