syslog test: Don't assert that we see plain LF newlines

In at least some build configurations that target Windows, we see CRLF
newlines in the stderr of the subprocess. Leave the newlines unspecified
and let "*" match them.

Signed-off-by: Simon McVittie <smcv@collabora.com>
Resolves: dbus/dbus#243
Status Job ID Name Coverage
  Build
manual #56797
allowed to fail manual
build:buster
canceled #56791
build:cmake

canceled #56788
build:debug

manual #56793
allowed to fail manual
build:i686-w64-mingw32-cmake
canceled #56792
build:i686-w64-mingw32-debug

manual #56796
allowed to fail manual
build:jessie
manual #56790
allowed to fail manual
build:legacy
canceled #56787
build:production

manual #56789
allowed to fail manual
build:reduced
canceled #56794
build:x86_64-w64-mingw32

canceled #56795
build:x86_64-w64-mingw32-cmake-debug

manual #56798
allowed to fail manual
build:xenial