update pytest check

Makefile

@@ -230,7 +230,7 @@ check:
 	$(MAKE) pytest
 
 pytest: $(ALL_PROGRAMS)
-ifndef PYTEST
+ifeq ($(PYTEST),)
 	@echo "py.test is required to run the integration tests, please install using 'pip3 install -r tests/requirements.txt', and rerun 'configure'."
 	exit 1
 else

configure

@@ -62,7 +62,11 @@ usage()
 
 add_var()
 {
-    echo "Setting $1... $2"
+    if [ -n "$2" ]; then
+        echo "Setting $1... $2"
+    else
+        echo "$1 not found"
+    fi
     echo "$1=$2" >> $CONFIG_VAR_FILE
     [ -z "$3" ] || echo "#define $1 $2" >> "$3"
 }