If two targets using the same OS are built in parallel,
they can both try to install the same include/os/* file
at the same time, causing the installEpics.pl script to
die. We fix this by making all installations atomic:
First copy the file to the installation directory using
a unique name, then rename it to the target name. The
target name is in the same directory and filesystem as
the temporary name, so the rename should be atomic.
Andrew Johnson
d72b4a3c1e