Make improvements

third_party/gdtoa/gdtoa_fltrnds.inc

@@ -0,0 +1,18 @@
+	FPI *fpi, fpi1;
+	int Rounding;
+#ifdef Trust_FLT_ROUNDS /*{{ only define this if FLT_ROUNDS really works! */
+	Rounding = Flt_Rounds;
+#else /*}{*/
+	Rounding = 1;
+	switch(fegetround()) {
+	  case FE_TOWARDZERO:	Rounding = 0; break;
+	  case FE_UPWARD:	Rounding = 2; break;
+	  case FE_DOWNWARD:	Rounding = 3;
+	  }
+#endif /*}}*/
+	fpi = &fpi0;
+	if (Rounding != 1) {
+		fpi1 = fpi0;
+		fpi = &fpi1;
+		fpi1.rounding = Rounding;
+		}