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

fusl/src/math/frexpf.c

Index: fusl/src/math/frexpf.c
diff --git a/fusl/src/math/frexpf.c b/fusl/src/math/frexpf.c
new file mode 100644
index 0000000000000000000000000000000000000000..0787097527c22a4be256abb600b9a05061a2ec87
--- /dev/null
+++ b/fusl/src/math/frexpf.c
@@ -0,0 +1,23 @@
+#include <math.h>
+#include <stdint.h>
+
+float frexpf(float x, int *e)
+{
+	union { float f; uint32_t i; } y = { x };
+	int ee = y.i>>23 & 0xff;
+
+	if (!ee) {
+		if (x) {
+			x = frexpf(x*0x1p64, e);
+			*e -= 64;
+		} else *e = 0;
+		return x;
+	} else if (ee == 0xff) {
+		return x;
+	}
+
+	*e = ee - 0x7e;
+	y.i &= 0x807ffffful;
+	y.i |= 0x3f000000ul;
+	return y.f;
+}