build: enable out_null on Windows
Since out_null is already Windows-compatible without any modifications,
this patch enables the compilation on Windows.
I confirmed it works fine on my Windows machine.
@@ -57,7 +57,7 @@ set(FLB_OUT_SPLUNK No)
set(FLB_OUT_STACKDRIVER No)
set(FLB_OUT_STDOUT Yes)
set(FLB_OUT_LIB No)
-set(FLB_OUT_NULL No)
+set(FLB_OUT_NULL Yes)
set(FLB_OUT_FLOWCOUNTER Yes)
set(FLB_OUT_KAFKA No)
set(FLB_OUT_KAFKA_REST No)
