Refrain from creating /etc/modprobe.conf if it does not already exist

Refrain from creating /etc/modprobe.conf if it does not already exist

Patch for alsaconf which makes it refrain from creating
/etc/modprobe.conf if the latter does not already exist.

Creating an empty /etc/modprobe.conf is bad because if it
exists then modprobe uses _only_ this file -- it does not
use /etc/modprobe.d/.

Additionally, this patch makes alsaconf set the cleanup
trap before it creates temporary files rather than after.

Signed-off-by: Thomas Hood <jdthood@yahoo.co.uk>