Realloc: Make behavior of realloc(ptr, 0) configurable.

test/unit/zero_realloc_abort.c

@@ -0,0 +1,26 @@
+#include "test/jemalloc_test.h"
+
+#include <signal.h>
+
+static bool abort_called = false;
+
+void set_abort_called() {
+	abort_called = true;
+};
+
+TEST_BEGIN(test_realloc_abort) {
+	abort_called = false;
+	safety_check_set_abort(&set_abort_called);
+	void *ptr = mallocx(42, 0);
+	assert_ptr_not_null(ptr, "Unexpected mallocx error");
+	ptr = realloc(ptr, 0);
+	assert_true(abort_called, "Realloc with zero size didn't abort");
+}
+TEST_END
+
+int
+main(void) {
+	return test(
+	    test_realloc_abort);
+}
+