newlib cris: Fix compilation warnings that recent gcc treats as errors

For the newlib part, warnings are all from lack of sync between
libc/machine/cris/sys/signal.h and libc/include/sys/signal.h.  This
commit gets them sufficiently in sync again, functionality-wise and
declaration-wise.  Still, nothing is declared that isn't supported at
the system level (i.e. in libgloss system calls and handled by the
CRIS simulator in the gdb project).

newlib/libc/machine/cris/sys/signal.h

@@ -12,6 +12,8 @@ extern "C" {
 #endif
 
 #include "_ansi.h"
+#include <sys/features.h>
+#include <sys/types.h>
 
 typedef unsigned long sigset_t;
 
@@ -32,21 +34,50 @@ struct sigaction {
 
 /* Adjusted to glibc; other values.  */
 #define SA_NOCLDSTOP 1	/* only value supported now for sa_flags */
+
+#if __POSIX_VISIBLE
 #define SIG_SETMASK 2	/* set mask with sigprocmask() */
 #define SIG_BLOCK 0	/* set of signals to block */
 #define SIG_UNBLOCK 1	/* set of signals to, well, unblock */
 
+int sigprocmask (int __how, const sigset_t *__a, sigset_t *__b);
+#endif	/* __POSIX_VISIBLE */
+
+#ifdef _LIBC
+int _kill (pid_t, int);
+#endif
+
+#if __POSIX_VISIBLE
+
+int kill (pid_t, int);
+int sigaddset (sigset_t *, const int);
+int sigdelset (sigset_t *, const int);
+int sigismember (const sigset_t *, int);
+int sigfillset (sigset_t *);
+int sigemptyset (sigset_t *);
+
 /* These depend upon the type of sigset_t, which right now
    is always a long.. They're in the POSIX namespace, but
    are not ANSI. */
-#define sigaddset(what,sig) (*(what) |= (1<<(sig)))
+#define sigaddset(what,sig) (*(what) |= (1<<(sig)), 0)
-#define sigemptyset(what)   (*(what) = 0)
+#define sigdelset(what,sig) (*(what) &= ~(1<<(sig)), 0)
+#define sigemptyset(what)   (*(what) = 0, 0)
+#define sigfillset(what)    (*(what) = ~(0), 0)
+#define sigismember(what,sig) (((*(what)) & (1<<(sig))) != 0)
 
-int sigprocmask (int __how, const sigset_t *__a, sigset_t *__b);
+#endif	/* __POSIX_VISIBLE */
+
+/* Using __MISC_VISIBLE until POSIX Issue 8 is officially released */
+#if __MISC_VISIBLE
+
+/* POSIX Issue 8 adds sig2str() and str2sig() */
+
+#define SIG2STR_MAX 17	/* (sizeof("RTMAX+") + sizeof("4294967295") - 1) */
+
+int sig2str(int, char *);
+int str2sig(const char *__restrict, int *__restrict);
 
-/* The first argument is really a pid_t, but that's just a typedef'd
+#endif /* __MISC_VISIBLE */
-   int, so let's avoid requiring sys/types only for this declaration.  */
-int kill (int, int);
 
 #define SIGHUP		 1
 #define SIGINT		 2