Silence make if nothing is to do for libcacard

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
diff --git a/libcacard/Makefile b/libcacard/Makefile
index 81d9eb5..a145569 100644
--- a/libcacard/Makefile
+++ b/libcacard/Makefile
@@ -27,6 +27,8 @@
 	rm -Rf .libs
 
 all: vscclient
+# Dummy command so that make thinks it has done something
+	@true
 
 #########################################################################
 # Rules for building libcacard standalone library