build: Put full download URLs in spec files

RPM only cares about the basename part of file names listed as sources,
so store the whole download URL in the spec file.

Signed-off-by: Euan Harris <euan.harris@citrix.com>
build: Remove -n options to the %setup macro where they are not necessary

If the source tarball expands to produce a directory called %{name}-%{version},
RPM will automatically use it.   -n is only needed when the directory produced
by the tarball has a name which doesn't fit this pattern.

Signed-off-by: Euan Harris <euan.harris@citrix.com>