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

fusl/src/complex/ccosl.c

Index: fusl/src/complex/ccosl.c
diff --git a/fusl/src/complex/ccosl.c b/fusl/src/complex/ccosl.c
new file mode 100644
index 0000000000000000000000000000000000000000..d787047fec8d5a8df1234f393cd2b8f1a683092b
--- /dev/null
+++ b/fusl/src/complex/ccosl.c
@@ -0,0 +1,13 @@
+#include "libm.h"
+
+#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
+long double complex ccosl(long double complex z)
+{
+	return ccos(z);
+}
+#else
+long double complex ccosl(long double complex z)
+{
+	return ccoshl(CMPLXL(-cimagl(z), creall(z)));
+}
+#endif