Fix missing include in libmv_bundle_adjuster on OSX.

- If compiling without glog (but with gflags) on OSX, unistd.h is
  required for close() et al, when using glog this was pulled in
  indirectly.

Change-Id: I8f0807d98479e386921fb48da30683d027d4bc61

examples/libmv_bundle_adjuster.cc

diff --git a/examples/libmv_bundle_adjuster.cc b/examples/libmv_bundle_adjuster.cc
index 6135c7f..0c6c0d6 100644
--- a/examples/libmv_bundle_adjuster.cc
+++ b/examples/libmv_bundle_adjuster.cc
@@ -99,7 +99,8 @@
 #  define close _close
 typedef unsigned __int32 uint32_t;
 #else
-# include <stdint.h>
+#include <stdint.h>
+#include <unistd.h>
 
 // O_BINARY is not defined on unix like platforms, as there is no
 // difference between binary and text files.