MNT: Suppress output from depend.mk rule

config/rules.mk

@@ -34,7 +34,7 @@ depend:
 # are to be saved into a separate build directory, the project
 # Makefile should set the CUDABUILDDIR variable.
 depend.mk:
-	echo "Building dependency file depend.mk" ; \
+	@echo "Building dependency file depend.mk" ; \
 	srcfiles=`find -name "*.c"  -or -name "*.cc"  -or -name "*.cxx" -or -name "*.cpp" -or -name "*.inc" -or -name "*.hpp" -or -name "*.cu"` ; \
 	for srcfile in ${srcfiles} dummyname; do                                \
 	  if [ -f "${srcfile}" ]; then                                          \