meson: use library() for libgstcheck instead of always building a shared lib

Otherwise we try to build a shared lib when we build the rest
of GStreamer statically, which won't work because we pass
-DGST_STATIC_COMPILATION when building statically, which means
we won't dllimport public symbols from our libs which means
that on Windows the unit tests will fail to link to libgstcheck.

https://bugzilla.gnome.org/show_bug.cgi?id=797185

libs/gst/check/meson.build

@@ -37,7 +37,7 @@ configure_file(input : 'libcheck/check.h.in',
   install_dir : join_paths(get_option('includedir'), 'gstreamer-1.0/gst/check'),
   configuration : check_cdata)
 
-gst_check = shared_library('gstcheck-@0@'.format(apiversion),
+gst_check = library('gstcheck-@0@'.format(apiversion),
   gst_check_sources,
   c_args : gst_c_args + ['-UG_DISABLE_ASSERT', '-DBUILDING_GST_CHECK'],
   version : libversion,