trigger: use "const char *" variables for result of string functions with const parameter

src/plugins/trigger/trigger-callback.c

@@ -810,8 +810,8 @@ trigger_callback_modifier_cb (const void *pointer, void *data,
                               const char *modifier, const char *modifier_data,
                               const char *string)
 {
-    const char *ptr_string;
-    char *string_modified, *pos, *buffer_pointer;
+    const char *ptr_string, *pos;
+    char *string_modified, *buffer_pointer;
     char *str_tags, **tags, *prefix, *string_no_color;
     unsigned long value;
     int num_tags, rc;

src/plugins/trigger/trigger-config.c

@@ -550,7 +550,8 @@ trigger_config_trigger_read_cb (const void *pointer, void *data,
                                 struct t_config_section *section,
                                 const char *option_name, const char *value)
 {
-    char *pos_option, *trigger_name;
+    const char *pos_option;
+    char *trigger_name;
     struct t_trigger *ptr_temp_trigger;
     int index_option;
 

src/plugins/trigger/trigger.c

@@ -239,8 +239,7 @@ trigger_search (const char *name)
 struct t_trigger *
 trigger_search_with_option (struct t_config_option *option)
 {
-    const char *ptr_name;
-    char *pos_option;
+    const char *ptr_name, *pos_option;
     struct t_trigger *ptr_trigger;
     int num_chars;