statistics: use namespace prefix osmo_counter*

Summary of changes:

s/struct counter/struct osmo_counter/g
s/counter_inc/osmo_counter_inc/g
s/counter_get/osmo_counter_get/g
s/counter_reset/osmo_counter_reset/g
s/counter_alloc/osmo_counter_alloc/g
s/counter_free/osmo_counter_free/g
s/counters_for_each/osmo_counters_for_each/g
diff --git a/include/osmocom/core/statistics.h b/include/osmocom/core/statistics.h
index 2c15965..1849327 100644
--- a/include/osmocom/core/statistics.h
+++ b/include/osmocom/core/statistics.h
@@ -1,33 +1,33 @@
 #ifndef _STATISTICS_H
 #define _STATISTICS_H
 
-struct counter {
+struct osmo_counter {
 	struct llist_head list;
 	const char *name;
 	const char *description;
 	unsigned long value;
 };
 
-static inline void counter_inc(struct counter *ctr)
+static inline void osmo_counter_inc(struct osmo_counter *ctr)
 {
 	ctr->value++;
 }
 
-static inline unsigned long counter_get(struct counter *ctr)
+static inline unsigned long osmo_counter_get(struct osmo_counter *ctr)
 {
 	return ctr->value;
 }
 
-static inline void counter_reset(struct counter *ctr)
+static inline void osmo_counter_reset(struct osmo_counter *ctr)
 {
 	ctr->value = 0;
 }
 
-struct counter *counter_alloc(const char *name);
-void counter_free(struct counter *ctr);
+struct osmo_counter *osmo_counter_alloc(const char *name);
+void osmo_counter_free(struct osmo_counter *ctr);
 
-int counters_for_each(int (*handle_counter)(struct counter *, void *), void *data);
+int osmo_counters_for_each(int (*handle_counter)(struct osmo_counter *, void *), void *data);
 
-struct counter *counter_get_by_name(const char *name);
+struct osmo_counter *osmo_counter_get_by_name(const char *name);
 
 #endif /* _STATISTICS_H */