Missing include for PATH_MAX.

Index: tests/torture.c
--- tests/torture.c.orig
+++ tests/torture.c
@@ -38,6 +38,7 @@
 
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>
+#include <limits.h>
 #elif (defined _WIN32) || (defined _WIN64)
 #include <direct.h>
 #include <io.h>