debug: removed noreturn attribute for panic calls

noreturn attribute was causing loss of stack information
during panic. This change allows getting more information
regarding a panic without having to reproduce it in a debug
environment.

Change-Id: I64e058effeef5394dcf6dc5213a2572fe11a54e1
diff --git a/include/debug.h b/include/debug.h
index 2944cb7..a9f3237 100644
--- a/include/debug.h
+++ b/include/debug.h
@@ -60,9 +60,9 @@
 int dgetc(char *c, bool wait);
 
 /* systemwide halts */
-void halt(void) __NO_RETURN;
+void halt(void);
 
-void _panic(void *caller, const char *fmt, ...) __PRINTFLIKE(2, 3) __NO_RETURN;
+void _panic(void *caller, const char *fmt, ...) __PRINTFLIKE(2, 3);
 #define panic(x...) _panic(__GET_CALLER(), x)
 
 #define PANIC_UNIMPLEMENTED panic("%s unimplemented\n", __PRETTY_FUNCTION__)