properly sync file's data on commit

this ensures that creator doesn't eat my config files on every crash.

Change-Id: I18f8135158e17d064774a49fe170b63c89517e49
Reviewed-by: Joerg Bornemann <joerg.bornemann@nokia.com>

src/libs/utils/savefile.cpp

@@ -31,6 +31,11 @@
 #include "savefile.h"
 #include "qtcassert.h"
 #include "fileutils.h"
+#ifdef Q_OS_WIN
+#  include <windows.h>
+#else
+#  include <unistd.h>
+#endif
 
 namespace Utils {
 
@@ -78,6 +83,15 @@ bool SaveFile::commit()
     QTC_ASSERT(!m_finalized, return false);
     m_finalized = true;
 
+    if (!flush()) {
+        remove();
+        return false;
+    }
+#ifdef Q_OS_WIN
+    FlushFileBuffers(handle());
+#else
+    fdatasync(handle());
+#endif
     close();
     if (error() != NoError) {
         remove();