ci: Set localstatedir to the system directory on CI machines

So the tests can access `/var/lib/dbus/machine-id`. This is not a
behaviour change relative to older behaviour on CI.

In future, it might make more sense to revert this commit and change the
CI scripts so they symlink
`/home/user/glib-installed/var/lib/dbus/machine-id` to the system
machine ID; or ensure that `/etc/machine-id` exists on all the CI
machines. That’s too complicated to do right now though.

Signed-off-by: Philip Withnall <pwithnall@endlessos.org>

.gitlab-ci.yml

@@ -74,6 +74,7 @@ fedora-x86_64:
             --werror
             --default-library=both
             --prefix=$HOME/glib-installed
+            --localstatedir=/var
             --libdir=lib
             -Dsystemtap=true
             -Ddtrace=true
@@ -117,6 +118,7 @@ debian-stable-x86_64:
             --werror
             --default-library=both
             --prefix=$HOME/glib-installed
+            --localstatedir=/var
             --libdir=lib
             -Dsystemtap=true
             -Ddtrace=true
@@ -461,6 +463,7 @@ scan-build:
             --werror
             --default-library=both
             --prefix=$HOME/glib-installed
+            --localstatedir=/var
             --libdir=lib
             -Dsystemtap=true
             -Ddtrace=true
@@ -487,6 +490,7 @@ coverity:
             --werror
             --default-library=both
             --prefix=$HOME/glib-installed
+            --localstatedir=/var
             --libdir=lib
             -Dsystemtap=true
             -Ddtrace=true