Explicitly include <sys/types.h> before including <regex.h>. This is

apparently required by POSIX.  It will be required in practice when
the bogus inclusion of <sys/types.h> is removed from <stdio.h>.

bin/expr/expr.y

@@ -484,6 +484,7 @@ struct val *a, *b;
 	return r;
 }
 	
+#include <sys/types.h>
 #include <regex.h>
 
 struct val *