Fedora downstream patches

[zdohnal]

Hi,

I saw the announcement on the OpenPrinting News, so when I was rebasing the package, I found out several downstream patches which can be handy for others.

They are split into three commits:

1. Add DeviceIDs into PPD files, which were gathered from users and they were missing in the original PPDs - helps system-config-printer to find the best driver available, but it can have other uses as well,
2. Update modules.mk to accept build system LDFLAGS - useful if the distro has specific flags which need to be used when linking the project,
3. Switch splix to pkg-config instead of cups-config - the cups-config tool is deprecated for several years and will be removed in the next major CUPS release, and its replacement is available with CUPS 2.4.x series, so we can use that from now.

Do you think they are useful to be merged? Do let me know if I should update something.

Zdenek