Don't duplicate ceiling() for every POSIX platform.

src/platform-posix.cc

Index: src/platform-posix.cc
diff --git a/src/platform-posix.cc b/src/platform-posix.cc
index 864e94c7e4f6896d61da24714332f3e2d55b35c8..6ac507204f966e4ea21610ca73d4dab0aa1f7e3e 100644
--- a/src/platform-posix.cc
+++ b/src/platform-posix.cc
@@ -210,6 +210,16 @@ void OS::DebugBreak() {
 // ----------------------------------------------------------------------------
 // Math functions
 
+double ceiling(double x) {
+  // Correct buggy 'ceil' on some systems (i.e. FreeBSD, OS X)
+  if (-1.0 < x && x < 0.0) {

[Sven Panne, 2013/07/25 08:32:46]

A ternary expresses the functional nature a bit more directly:

return (-1.0 < x && x < 0.0) ? -0.0 : ceil(x);

+    return -0.0;
+  } else {
+    return ceil(x);
+  }
+}
+
+
 double modulo(double x, double y) {
   return fmod(x, y);
 }