Change type of {s,t}print_open_modes's argument to unsigned

As "flags" argument of sprint_open_modes and tprint_open_modes is
involved only in bit operations, change its type to unsigned.

* defs.h.c (sprint_open_modes, tprint_open_modes): Change type
to unsigned int.
* open.c (sprint_open_modes, tprint_open_modes): Likewise.
diff --git a/defs.h b/defs.h
index eec0228..d1e8e1b 100644
--- a/defs.h
+++ b/defs.h
@@ -629,8 +629,8 @@
 extern void printsignal(int);
 extern void tprint_iov(struct tcb *, unsigned long, unsigned long, int decode_iov);
 extern void tprint_iov_upto(struct tcb *, unsigned long, unsigned long, int decode_iov, unsigned long);
-extern void tprint_open_modes(int);
-extern const char *sprint_open_modes(int);
+extern void tprint_open_modes(unsigned int);
+extern const char *sprint_open_modes(unsigned int);
 extern void print_seccomp_filter(struct tcb *tcp, unsigned long);
 
 struct strace_statfs;