Add build date to LDFLAGS

Makefile

@@ -1,14 +1,19 @@
-LUME_VERSION ?= $(shell git describe --tags --always)
-LDFLAGS := ${LDFLAGS} -X git.kill0.net/chill9/lume/cmd.Version=${LUME_VERSION}
 
 ifeq ($(OS), Windows_NT)
     EXE=lume.exe
 	RM=del /f /q
+	BUILD_DATE=$(shell powershell Get-Date -Format "yyyy-MM-ddThh:mm:sszzz")
 else
     EXE=lume
     EXE=rm -f
+	BUILD_DATE=$(shell date --iso-8601=seconds)
 endif
 
+LUME_VERSION ?= $(shell git describe --tags --always)
+LDFLAGS := ${LDFLAGS} \
+	-X git.kill0.net/chill9/lume/cmd.Version=${LUME_VERSION} \
+	-X git.kill0.net/chill9/lume/cmd.BuildDate=${BUILD_DATE}
+
 .PHONY: build
 build:
 	go build -o ${EXE} -ldflags="${LDFLAGS}" ./cmd/lume