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

fusl/src/math/__fpclassifyf.c

Index: fusl/src/math/__fpclassifyf.c
diff --git a/fusl/src/math/__fpclassifyf.c b/fusl/src/math/__fpclassifyf.c
new file mode 100644
index 0000000000000000000000000000000000000000..fd00eb1bcdc62e08c2ed1c8bdb8ac09dce3d0b52
--- /dev/null
+++ b/fusl/src/math/__fpclassifyf.c
@@ -0,0 +1,11 @@
+#include <math.h>
+#include <stdint.h>
+
+int __fpclassifyf(float x)
+{
+	union {float f; uint32_t i;} u = {x};
+	int e = u.i>>23 & 0xff;
+	if (!e) return u.i<<1 ? FP_SUBNORMAL : FP_ZERO;
+	if (e==0xff) return u.i<<9 ? FP_NAN : FP_INFINITE;
+	return FP_NORMAL;
+}