gqsort: Move test to glib/tests/

Previously tests existed in two places,
`$top_srcdir/tests/qsort-test.c` contained a similar test
to the one in `$top_srcdir/glib/tests/sort.c` called `test_sort_basic()`

The test for checking with zero elements was additional added to
`$top_srcdir/glib/tests/sort.c` and `$top_srcdir/tests/qsort-test.c`
was deleted.

Related to: #1434

tests/meson.build

@@ -30,7 +30,6 @@ tests = {
   'mapping-test' : {},
   'onceinit' : {},
   'asyncqueue-test' : {},
-  'qsort-test' : {},
   'relation-test' : {},
   'slice-concurrent' : {},
   'slice-threadinit' : {