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

fusl/src/math/remainderl.c

Index: fusl/src/math/remainderl.c
diff --git a/fusl/src/math/remainderl.c b/fusl/src/math/remainderl.c
new file mode 100644
index 0000000000000000000000000000000000000000..2a13c1d5af138b8b9607e82c724c3d81f4f3ddd7
--- /dev/null
+++ b/fusl/src/math/remainderl.c
@@ -0,0 +1,15 @@
+#include <math.h>
+#include <float.h>
+
+#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
+long double remainderl(long double x, long double y)
+{
+	return remainder(x, y);
+}
+#else
+long double remainderl(long double x, long double y)
+{
+	int q;
+	return remquol(x, y, &q);
+}
+#endif