Fix a few Sparse warnings

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@7016 c046a42c-6fe2-441c-8c8c-71466251a162
diff --git a/cmd.h b/cmd.h
index 5ca8fcf..c5be50f 100644
--- a/cmd.h
+++ b/cmd.h
@@ -75,4 +75,6 @@
 
 extern void	timestr(struct timeval *tv, char *str, size_t sz, int flags);
 
+extern char *progname;
+
 #endif	/* __COMMAND_H__ */