libs/store: make build without PTHREAD_STACK_MIN

On NetBSD, PTHREAD_STACK_MIN is not available.
If PTHREAD_STACK_MIN is not defined, define it to 0 so that we fallback to
DEFAULT_THREAD_STACKSIZE

Signed-off-by: Manuel Bouyer <bouyer@netbsd.org>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>

tools/libs/store/xs.c

@@ -811,6 +811,11 @@ bool xs_watch(struct xs_handle *h, const char *path, const char *token)
 
 #ifdef USE_PTHREAD
 #define DEFAULT_THREAD_STACKSIZE (16 * 1024)
+/* NetBSD doesn't have PTHREAD_STACK_MIN. */
+#ifndef PTHREAD_STACK_MIN
+# define PTHREAD_STACK_MIN 0
+#endif
+
 #define READ_THREAD_STACKSIZE 					\
 	((DEFAULT_THREAD_STACKSIZE < PTHREAD_STACK_MIN) ? 	\
 	PTHREAD_STACK_MIN : DEFAULT_THREAD_STACKSIZE)