fix missing prototypes/wrong signature for psiginfo, psignal

include/signal.h

@@ -87,6 +87,9 @@ int sigqueue(pid_t, int, const union sigval);
 int pthread_sigmask(int, const sigset_t *, sigset_t *);
 int pthread_kill(pthread_t, int);
 
+void psiginfo(const siginfo_t *, const char *);
+void psignal(int, const char *);
+
 #endif
 
 #if defined(_XOPEN_SOURCE) || defined(_GNU_SOURCE)

src/signal/psiginfo.c

@@ -2,7 +2,7 @@
 #include <string.h>
 #include <signal.h>
 
-void psiginfo(siginfo_t *si, const char *msg)
+void psiginfo(const siginfo_t *si, const char *msg)
 {
 	char *s = strsignal(si->si_signo);
 	if (msg) fprintf(stderr, "%s: %s\n", msg, s);