Avoid calling catclose with an invalid argumentnits

POSIX doesn't specify that catclose should accept -1 as argument, and with
musl (1.2.4 and earlier at least) it causes a segfault.

1 files changed, 2 insertions, 1 deletions

diff --git a/z01.c b/z01.c
index f18d4ce..d4953b8 100644
--- a/z01.c
+++ b/z01.c
@@ -974,7 +974,8 @@ int main(int argc, char *argv[])
   while( run_num <= runs_to_do );
 
 #if LOCALE_ON
-  catclose(MsgCat);
+  if (MsgCat != (nl_catd)-1)
+    catclose(MsgCat);
 #endif
 
   exit(0);