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

fusl/src/math/fmax.c

Index: fusl/src/math/fmax.c
diff --git a/fusl/src/math/fmax.c b/fusl/src/math/fmax.c
new file mode 100644
index 0000000000000000000000000000000000000000..94f0caa17751b63d46e6826d37e63923dc468484
--- /dev/null
+++ b/fusl/src/math/fmax.c
@@ -0,0 +1,13 @@
+#include <math.h>
+
+double fmax(double x, double y)
+{
+	if (isnan(x))
+		return y;
+	if (isnan(y))
+		return x;
+	/* handle signed zeros, see C99 Annex F.9.9.2 */
+	if (signbit(x) != signbit(y))
+		return signbit(x) ? y : x;
+	return x < y ? y : x;
+}