adding __math_xflowf

src/libc-shim/src/__math_xflowf.c

@@ -0,0 +1,8 @@
+#include "libm.h"
+
+float __math_xflowf(uint32_t sign, float y)
+{
+    // NOTE(orca): no fp barriers
+    // return eval_as_double(fp_barrier(sign ? -y : y) * y);
+    return eval_as_float((sign ? -y : y) * y);
+}