API: Provide dummy halt() in the glue layer.

This fixes a demo app link failure on platforms configured with CONFIG_PANIC_HANG.

Signed-off-by: Rafal Jaworowski <raj@semihalf.com>
diff --git a/api_examples/libgenwrap.c b/api_examples/libgenwrap.c
index df62633..2b62bad 100644
--- a/api_examples/libgenwrap.c
+++ b/api_examples/libgenwrap.c
@@ -84,7 +84,12 @@
 	ub_reset();
 }
 
-void *malloc(size_t len)
+void *malloc (size_t len)
 {
 	return NULL;
 }
+
+void hang (void)
+{
+	while (1) ;
+}