Mac Yosemite compatibility with Qt 5.3.1

After I upgrade to Yosemite, my Qt application was not working,

You will get following build errors whenever you build QT app
"Could not resolve SDK path for 'macosx 10.8'"

so I have  to do a few hacks to make it work as follows

1) Open the following file
<Qt Installed Dir>/5.3/clang_64/mkspecs/qdevice.pri

2) Change the first line to
!host_build:QMAKE_MAC_SDK = macosx10.10

this will support QT on Yosemite.