use general stat function in C test

It's impossible to test that error mode with the C summary functions.

Also, rename `tsk_treeseq_two_locus_count_general_stat` to
`tsk_treeseq_two_locus_general_count_stat`. It makes more sense this
way.

Author: lkirk

c/tests/test_stats.c

@@ -3680,8 +3680,9 @@ test_two_locus_stat_input_errors(void)
         row_sites, NULL, num_sites, col_sites, NULL, 0, result);
     CU_ASSERT_EQUAL_FATAL(ret, 0);
 
-    ret = tsk_treeseq_r2(&ts, num_sample_sets, 0, sample_sets, num_sites, row_sites,
-        NULL, num_sites, col_sites, NULL, 0, result);
+    ret = tsk_treeseq_two_locus_general_count_stat(&ts, num_sample_sets,
+        sample_set_sizes, sample_sets, 0, NULL, NULL, NULL, num_sites, row_sites, NULL,
+        num_sites, col_sites, NULL, 0, result);
     CU_ASSERT_EQUAL_FATAL(ret, TSK_ERR_BAD_RESULT_DIMS);
 
     ret = tsk_treeseq_r2(&ts, 1, sample_set_sizes, sample_sets, num_sites, row_sites,

c/tskit/trees.c

@@ -3392,7 +3392,7 @@ check_sample_set_dups(tsk_size_t num_sample_sets, const tsk_size_t *sample_set_s
 
 /* Called directly by C python interface `two_locus_count_stat` */
 int
-tsk_treeseq_two_locus_count_general_stat(const tsk_treeseq_t *self,
+tsk_treeseq_two_locus_general_count_stat(const tsk_treeseq_t *self,
     tsk_size_t num_sample_sets, const tsk_size_t *sample_set_sizes,
     const tsk_id_t *sample_sets, tsk_size_t result_dim, general_stat_func_t *f,
     void *f_params, norm_func_t *norm_f, tsk_size_t out_rows, const tsk_id_t *row_sites,
@@ -3466,7 +3466,7 @@ tsk_treeseq_two_locus_count_general_stat(const tsk_treeseq_t *self,
     return ret;
 }
 
-/* Wrapper of `tsk_treeseq_two_locus_count_general_stat` for C summary Functions */
+/* Wrapper of `tsk_treeseq_two_locus_general_count_stat` for C summary Functions */
 static int
 tsk_treeseq_two_locus_count_stat(const tsk_treeseq_t *self, tsk_size_t num_sample_sets,
     const tsk_size_t *sample_set_sizes, const tsk_id_t *sample_sets,
@@ -3479,7 +3479,7 @@ tsk_treeseq_two_locus_count_stat(const tsk_treeseq_t *self, tsk_size_t num_sampl
         .num_sample_sets = num_sample_sets,
         .sample_set_sizes = sample_set_sizes,
         .set_indexes = set_indexes };
-    return tsk_treeseq_two_locus_count_general_stat(self, num_sample_sets,
+    return tsk_treeseq_two_locus_general_count_stat(self, num_sample_sets,
         sample_set_sizes, sample_sets, result_dim, f, &f_params, norm_f, out_rows,
         row_sites, row_positions, out_cols, col_sites, col_positions, options, result);
 }

c/tskit/trees.h

@@ -1112,7 +1112,7 @@ typedef int general_sample_stat_method(const tsk_treeseq_t *self,
     const tsk_id_t *sample_sets, tsk_size_t num_indexes, const tsk_id_t *indexes,
     tsk_size_t num_windows, const double *windows, tsk_flags_t options, double *result);
 
-int tsk_treeseq_two_locus_count_general_stat(const tsk_treeseq_t *self,
+int tsk_treeseq_two_locus_general_count_stat(const tsk_treeseq_t *self,
     tsk_size_t num_sample_sets, const tsk_size_t *sample_set_sizes,
     const tsk_id_t *sample_sets, tsk_size_t result_dim, general_stat_func_t *f,
     void *f_params, norm_func_t *norm_f, tsk_size_t out_rows, const tsk_id_t *row_sites,

python/_tskitmodule.c

@@ -8196,7 +8196,7 @@ TreeSequence_two_locus_count_stat(TreeSequence *self, PyObject *args, PyObject *
         .summary_func = summary_func,
         .norm_func = norm_func,
     };
-    err = tsk_treeseq_two_locus_count_general_stat(self->tree_sequence, num_sample_sets,
+    err = tsk_treeseq_two_locus_general_count_stat(self->tree_sequence, num_sample_sets,
         PyArray_DATA(sample_set_sizes_array), PyArray_DATA(sample_sets_array),
         output_dim, general_two_locus_count_stat_func, params,
         general_two_locus_norm_func, result_dim[0], row_sites_parsed,