(UNSTABLE) add signal.h

Author: ZERICO2005

src/libc/header_test.c

@@ -12,6 +12,7 @@
 #include <limits.h>
 #include <math.h>
 #include <setjmp.h>
+#include <signal.h>
 #include <stdalign.h>
 #include <stdarg.h>
 #include <stdbit.h>

src/libc/include/signal.h

@@ -0,0 +1,14 @@
+#ifndef _SETJMP_H
+#define _SETJMP_H
+
+#include <cdefs.h>
+
+__BEGIN_DECLS
+
+void (*signal(int sig, void (*func)(int)))(int);
+
+int raise(int sig);
+
+__END_DECLS
+
+#endif /* _SETJMP_H */