fix: Makefile OS conditional

Author: Bobby Tiernay

.gitignore

@@ -7,3 +7,4 @@ junit*.xml
 debug.test
 /output/
 coverage.out
+.idea/

Makefile

@@ -65,9 +65,9 @@ IMAGE:=$(REGISTRY)/node-problem-detector:$(TAG)
 # support needs libsystemd-dev or libsystemd-journal-dev.
 ENABLE_JOURNALD?=1
 
-ifeq ($(go env GOHOSTOS), darwin)
+ifeq ($(shell go env GOHOSTOS), darwin)
 ENABLE_JOURNALD=0
-else ifeq ($(go env GOHOSTOS), windows)
+else ifeq ($(shell go env GOHOSTOS), windows)
 ENABLE_JOURNALD=0
 endif