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

fusl/src/math/exp10.c

+#define _GNU_SOURCE
+#include <math.h>
+#include <stdint.h>
+#include "libc.h"
+
+double exp10(double x)
+{
+        static const double p10[] = {
+                1e-15, 1e-14, 1e-13, 1e-12, 1e-11, 1e-10,
+                1e-9, 1e-8, 1e-7, 1e-6, 1e-5, 1e-4, 1e-3, 1e-2, 1e-1,
+                1, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6, 1e7, 1e8, 1e9,
+                1e10, 1e11, 1e12, 1e13, 1e14, 1e15
+        };
+        double n, y = modf(x, &n);
+        union {double f; uint64_t i;} u = {n};
+        /* fabs(n) < 16 without raising invalid on nan */
+        if ((u.i>>52 & 0x7ff) < 0x3ff+4) {
+                if (!y) return p10[(int)n+15];
+                y = exp2(3.32192809488736234787031942948939 * y);
+                return y * p10[(int)n+15];
+        }
+        return pow(10.0, x);
+}
+
+weak_alias(exp10, pow10);