Rename struct avl to avl_element and the typedef to avl_t (#10735)

Before:

```
struct foobar {
    avl avl;
    ...
}
```

After:

```
struct foobar {
    avl_t avl;
    ...
};
```

Which makes figuring out the type from field name easier.

1 files changed, 1 insertions, 1 deletions

diff --git a/health/health_log.c b/health/health_log.c
index 8c0bc5c34f..de216c89a1 100644
--- a/health/health_log.c
+++ b/health/health_log.c
@@ -243,7 +243,7 @@ static inline ssize_t health_alarm_log_read(RRDHOST *host, FILE *fp, const char
                 RRDCALC *rc = alarm_max_last_repeat(host, alarm_name,simple_hash(alarm_name));
                 if (!rc) {
                     for(rc = host->alarms; rc ; rc = rc->next) {
-                        RRDCALC *rdcmp  = (RRDCALC *) avl_insert_lock(&(host)->alarms_idx_name, (avl *)rc);
+                        RRDCALC *rdcmp  = (RRDCALC *) avl_insert_lock(&(host)->alarms_idx_name, (avl_t *)rc);
                         if(rdcmp != rc) {
                             error("Cannot insert the alarm index ID using log %s", rc->name);
                         }