5875 psignal and psiginfo should not be exposed in environments prior to POSIX 2008

@@ -50,12 +50,14 @@
 extern const char *_sys_traplist[];
 extern const char *_sys_cldlist[];
 extern const struct siginfolist *_sys_siginfolistp;
 #define _sys_siginfolist        _sys_siginfolistp
 
+#if defined(_XPG7) || !defined(_STRICT_SYMBOLS)
 extern void psignal(int, const char *);
 extern void psiginfo(const siginfo_t *, const char *);
+#endif
 
 #ifdef  __cplusplus
 }
 #endif