Correct NetBSD build issue
Cast SIG_IGN to (uptr).
SIG_IGN is defined on NetBSD as a function pointer and cannot be
assigned to an integer as it is.
sys/signal.h:#define       SIG_IGN         ((void (*)(int))  1)
@@ -105,7 +105,7 @@ unsigned struct_msqid_ds_sz = sizeof(struct msqid_ds);
unsigned struct_mq_attr_sz = sizeof(struct mq_attr);
unsigned struct_statvfs_sz = sizeof(struct statvfs);
-const uptr sig_ign = SIG_IGN;
+const uptr sig_ign = (uptr)SIG_IGN;
const uptr sig_dfl = (uptr)SIG_DFL;
const uptr sig_err = (uptr)SIG_ERR;
const uptr sa_siginfo = (uptr)SA_SIGINFO;
