Restructure setters for profiling info

Explicitly define three setters:

- `prof_tctx_reset()`: set `prof_tctx` to `1U`, if we don't know in
advance whether the allocation is large or not;
- `prof_tctx_reset_sampled()`: set `prof_tctx` to `1U`, if we already
know in advance that the allocation is large;
- `prof_info_set()`: set a real `prof_tctx`, and also set other
profiling info e.g. the allocation time.

Code structure wise, the prof level is kept as a thin wrapper, the
large level only provides low level setter APIs, and the arena level
carries out the main logic.

src/large.c

@@ -372,7 +372,7 @@ large_prof_info_get(const extent_t *extent, prof_info_t *prof_info) {
 	extent_prof_info_get(extent, prof_info);
 }
 
-void
+static void
 large_prof_tctx_set(extent_t *extent, prof_tctx_t *tctx) {
 	extent_prof_tctx_set(extent, tctx);
 }
@@ -383,6 +383,9 @@ large_prof_tctx_reset(extent_t *extent) {
 }
 
 void
-large_prof_alloc_time_set(extent_t *extent, nstime_t *t) {
-	extent_prof_alloc_time_set(extent, t);
+large_prof_info_set(extent_t *extent, prof_tctx_t *tctx) {
+	large_prof_tctx_set(extent, tctx);
+	nstime_t t;
+	nstime_init_update(&t);
+	extent_prof_alloc_time_set(extent, &t);
 }

src/prof.c

@@ -162,13 +162,7 @@ prof_alloc_rollback(tsd_t *tsd, prof_tctx_t *tctx, bool updated) {
 void
 prof_malloc_sample_object(tsd_t *tsd, const void *ptr, size_t usize,
     prof_tctx_t *tctx) {
-	prof_tctx_set(tsd, ptr, NULL, tctx);
-
-	/* Get the current time and set this in the extent_t. We'll read this
-	 * when free() is called. */
-	nstime_t t;
-	nstime_init_update(&t);
-	prof_alloc_time_set(tsd, ptr, &t);
+	prof_info_set(tsd, ptr, tctx);
 
 	malloc_mutex_lock(tsd_tsdn(tsd), tctx->tdata->lock);
 	tctx->cnts.curobjs++;