libyang REFACTOR avoid connection between context and log location storage

libyang works strictly with a single context now, so it is not necessary
to connect the log location information with a specific context. It also
clarifies what to do when the context is not available in the function
but still a location information in an error message could be useful.
diff --git a/src/xpath.c b/src/xpath.c
index 89aa0d0..2e2e314 100644
--- a/src/xpath.c
+++ b/src/xpath.c
@@ -4592,9 +4592,9 @@
 
     LY_ARRAY_NEW_RET(set->ctx, patterns, pattern, LY_EMEM);
     *pattern = malloc(sizeof **pattern);
-    LOG_LOCSET(set->ctx, NULL, set->cur_node, NULL, NULL);
+    LOG_LOCSET(NULL, set->cur_node, NULL, NULL);
     rc = lys_compile_type_pattern_check(set->ctx, args[1]->val.str, &(*pattern)->code);
-    LOG_LOCBACK(set->ctx, 0, 1, 0, 0);
+    LOG_LOCBACK(0, 1, 0, 0);
     if (rc != LY_SUCCESS) {
         LY_ARRAY_FREE(patterns);
         return rc;
@@ -8489,7 +8489,7 @@
     set->format = format;
     set->prefix_data = prefix_data;
 
-    LOG_LOCSET(set->ctx, NULL, set->cur_node, NULL, NULL);
+    LOG_LOCSET(NULL, set->cur_node, NULL, NULL);
 
     /* evaluate */
     rc = eval_expr_select(exp, &tok_idx, 0, set, options);
@@ -8497,7 +8497,7 @@
         lyxp_set_free_content(set);
     }
 
-    LOG_LOCBACK(set->ctx, 0, 1, 0, 0);
+    LOG_LOCBACK(0, 1, 0, 0);
     return rc;
 }
 
@@ -8758,12 +8758,12 @@
     set->format = format;
     set->prefix_data = prefix_data;
 
-    LOG_LOCSET(set->ctx, set->cur_scnode, NULL, NULL, NULL);
+    LOG_LOCSET(set->cur_scnode, NULL, NULL, NULL);
 
     /* evaluate */
     ret = eval_expr_select(exp, &tok_idx, 0, set, options);
 
-    LOG_LOCBACK(set->ctx, 1, 0, 0, 0);
+    LOG_LOCBACK(1, 0, 0, 0);
     return ret;
 }