Use GOHOSTOS to switch journald plugin build

This plugin requires libsystemd to compile, which is only available on
Linux. This uses `go env` to determine if the current build platform can
support this or not, and if not, disables the building of the plugin to
allow compilation on Windows and macOS platforms.

Signed-off-by: Sean McGinnis <[email protected]>

Author: stmcginnis

Makefile

@@ -53,7 +53,9 @@ IMAGE:=$(REGISTRY)/node-problem-detector:$(TAG)
 # support needs libsystemd-dev or libsystemd-journal-dev.
 ENABLE_JOURNALD?=1
 
-ifeq ($(shell uname -s 2>/dev/null), Darwin)
+ifeq ($(go env GOHOSTOS), darwin)
+ENABLE_JOURNALD=0
+else ifeq ($(go env GOHOSTOS), windows)
 ENABLE_JOURNALD=0
 endif