Fix all of the tests.

src/test/perf/contention/contention.cc

@@ -100,7 +100,7 @@ void test_tasks_f(size_t id)
 
 void test_tasks(size_t num_tasks, size_t count, size_t size)
 {
-  Alloc* a = ThreadAlloc::get();
+  Alloc*& a = ThreadAlloc::get();
 
   contention = new std::atomic<size_t*>[size];
   xoroshiro::p128r32 r;

src/test/perf/external_pointer/externalpointer.cc

@@ -43,7 +43,7 @@ namespace test
 
   void test_external_pointer(xoroshiro::p128r64& r)
   {
-    auto* alloc = ThreadAlloc::get();
+    auto& alloc = ThreadAlloc::get();
 
     setup(r, alloc);