Index: b/usr/src/head/signal.h
===================================================================
--- a/usr/src/head/signal.h
+++ b/usr/src/head/signal.h
@@ -32,7 +32,7 @@
 #ifndef _SIGNAL_H
 #define	_SIGNAL_H
 
-#include <sys/feature_tests.h>
+#include <features.h>
 
 #if defined(__EXTENSIONS__) || !defined(_STRICT_STDC) || \
 	defined(__XOPEN_OR_POSIX)
@@ -56,6 +56,13 @@ using std::raise;
 extern "C" {
 #endif
 
+typedef void (*__sighandler_t)(int);
+#ifdef _GNU_SOURCE
+typedef __sighandler_t sighandler_t;
+#endif
+#ifdef __EXTENSIONS__
+typedef __sighandler_t sig_t;
+#endif
 
 extern const char	**_sys_siglistp;	/* signal descriptions */
 extern const int	_sys_siglistn;		/* # of signal descriptions */