BUILD: debug: make gcc not complain on the ABORT_NOW() macro

On recent gcc versions with the null-deref checks, ABORT_NOW() rightfully
emits such a warning. But here it's on purpose. Simply changing the memory
address to 1 makes gcc happy.
diff --git a/include/common/debug.h b/include/common/debug.h
index 325ef83..8f6d123 100644
--- a/include/common/debug.h
+++ b/include/common/debug.h
@@ -40,7 +40,7 @@
 /* This abort is more efficient than abort() because it does not mangle the
  * stack and stops at the exact location we need.
  */
-#define ABORT_NOW() (*(volatile int*)0=0)
+#define ABORT_NOW() (*(volatile int*)1=0)
 
 /* this one is provided for easy code tracing.
  * Usage: TRACE(strm||0, fmt, args...);