Fix assertion in malloc.c:tcache_get

[Joseph Myers <joseph at codesourcery dot com>]

One of the warnings that appears with -Wextra is "ordered comparison
of pointer with integer zero" in malloc.c:tcache_get, for the
assertion:

  assert (tcache->entries[tc_idx] > 0);

Indeed, a "> 0" comparison does not make sense for
tcache->entries[tc_idx], which is a pointer.  My guess is that
tcache->counts[tc_idx] is what's intended here, and this patch changes
the assertion accordingly.

Tested for x86_64.

2019-02-04  Joseph Myers  <joseph@codesourcery.com>

	* malloc/malloc.c (tcache_get): Compare tcache->counts[tc_idx]
	with 0, not tcache->entries[tc_idx].

diff --git a/malloc/malloc.c b/malloc/malloc.c
index feaf7ee0bf..13fc1f2049 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -2946,7 +2946,7 @@ tcache_get (size_t tc_idx)
 {
   tcache_entry *e = tcache->entries[tc_idx];
   assert (tc_idx < TCACHE_MAX_BINS);
-  assert (tcache->entries[tc_idx] > 0);
+  assert (tcache->counts[tc_idx] > 0);
   tcache->entries[tc_idx] = e->next;
   --(tcache->counts[tc_idx]);
   e->key = NULL;

-- 
Joseph S. Myers
joseph@codesourcery.com