Modify FastD2I to use static_cast instead of lrint(). Benchmarks show that it...

src/conversions.h

Index: src/conversions.h
===================================================================
--- src/conversions.h	(revision 4210)
+++ src/conversions.h	(working copy)
@@ -36,7 +36,12 @@
 // rounding towards zero.
 // The result is unspecified if x is infinite or NaN, or if the rounded
 // integer value is outside the range of type int.
-static inline int FastD2I(double x);
+static inline int FastD2I(double x) {
+  // The static_cast convertion from double to int used to be slow, but
+  // as new benchmarks show, now it is much faster than lrint().
+  return static_cast<int>(x);
+}
+
 static inline unsigned int FastD2UI(double x);