KristianRosenvold: Added a small script that fixes up git file change…

…d status after a build

I am hoping jarib will add something like this to CFB;

if (exists ~/.git){
   ./git-fixup
}

When the build is about to complete. Sorry about the notation ;)

r13801

.git-fixfiles

@@ -0,0 +1 @@
+git update-index --assume-unchanged cpp/prebuilt/**/*.so