include unistd.h if possible before attempting to define R_OK

diff --git a/ast_common.h.in b/ast_common.h.in
index f57967e51ac768cb8a536ca83026d12deea27844..e51fb61f4c47e4598f3a7f794a169540f4b59081 100644 (file)
--- a/ast_common.h.in
+++ b/ast_common.h.in
@@ -207,6 +207,10 @@ typedef int ssize_t;
 #endif
 #endif
 
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
 #ifndef MAXINT
 #define MAXINT INT_MAX
 #endif