Unit test for HTTP 500 Internal Server Error

Currently an internal server error can be triggered by accessing an
entry belonging to a redirect loop. The ZIM file (test/data/poor.zim)
containing such a loop was copied from openzim/zim-tools repository
(test/data/zimfiles/poor.zim).

test/meson.build

@@ -29,6 +29,7 @@ if gtest_dep.found() and not meson.is_cross_build()
       'zimfile.zim',
       'zimfile&other.zim',
       'corner_cases.zim',
+      'poor.zim',
       'library.xml'
     ]
     foreach file : data_files