fail cap checks if CONFIG_DEBUG_BUILD is not set

Signed-off-by: Axel Heider <axelheider@gmx.de>
(cherry picked from commit fcbc1944a948c651cabaa509c55dc0dcdf3ed377)

Change-Id: I75c19cd32e6712bb56c88c59d3cd36751297a289
diff --git a/libsel4debug/include/sel4debug/debug.h b/libsel4debug/include/sel4debug/debug.h
index 7b2b04d..53aac59 100644
--- a/libsel4debug/include/sel4debug/debug.h
+++ b/libsel4debug/include/sel4debug/debug.h
@@ -29,21 +29,33 @@
 
 static inline int debug_cap_is_valid(seL4_CPtr cap)
 {
+#ifdef CONFIG_DEBUG_BUILD
     return (0 != seL4_DebugCapIdentify(cap));
+#else
+    return 0; /* fail check on non-debug kernels */
+#endif
 }
 
 static inline int debug_cap_is_endpoint(seL4_CPtr cap)
 {
+#ifdef CONFIG_DEBUG_BUILD
     // there is kernel/generated/arch/object/structures_gen.h that defines
     // cap_endpoint_cap = 4, but we can't include it here
     return (4 == seL4_DebugCapIdentify(cap));
+#else
+    return 0; /* fail check on non-debug kernels */
+#endif
 }
 
 static inline int debug_cap_is_notification(seL4_CPtr cap)
 {
+#ifdef CONFIG_DEBUG_BUILD
     // there is kernel/generated/arch/object/structures_gen.h that defines
     // cap_notification_cap = 6, but we can't include it here
     return (6 == seL4_DebugCapIdentify(cap));
+#else
+    return 0; /* fail check on non-debug kernels */
+#endif
 }
 
 
diff --git a/libsel4debug/src/caps.c b/libsel4debug/src/caps.c
index 49baa05..4d7d8fc 100644
--- a/libsel4debug/src/caps.c
+++ b/libsel4debug/src/caps.c
@@ -20,7 +20,8 @@
 {
 #ifdef CONFIG_DEBUG_BUILD
     int type = seL4_DebugCapIdentify(cap);
-
-    printf("Cap type number is %d\n", type);
-#endif /* CONFIG_DEBUG_BUILD */
+    printf("Cap %d has type %d\n", cap, type);
+#else
+    printf("DEBUG_BUILD not set, can't get type of cap %d", cap);
+#endif
 }