Galera spec files need to be updated to support openSUSE and SLES 15.0

We need to add support for openSUSE 15.0 and SLES 15.0 in the rpm .spec files for our galera packages.

In the ./scripts/packages/galera.spec and ./scripts/packages/galera-obs.spec files in our galera src repository have several bits of code to detect various SLES/openSUSE versions and set the 'dist' variable. For example this section to detect SLES/openSUSE 12:

%if 0%{?suse_version} == 1315

%define dist .sle12

%endif

According to https://en.opensuse.org/openSUSE:Build_Service_cross_distribution_howto it appears the appropriate code to do the same for SLES/openSUSE 15.0 would be this:

%if 0%{?sle_version} == 150000

%define dist .sle15

%endif

This one section should work for both SLES 15.0 and openSUSE 15.0. I'm not sure if there are other things that need to be done or not. But this at least does need to be added to the appropriate place in the spec files.

This error causes issues when it comes time to actually create the rpm. Instead of naming the tmp dir files are copied into to create the rpm something like 'galera-25.3.23-1.sle15.x86_64' it's naming the dir

galera-25.3.23-1%{dist}.x86_64

because the 'dist' variable is not set.

This weird directory name causes "file not found" errors when rpmbuild tries to process it. For example, see this log: https://buildbot.askmonty.org/buildbot/builders/kvm-zyp-sles150-amd64-gal/builds/3/steps/compile/logs/stdio