Add Makefile build

This prepares for multiple binaries and distribution builds

Makefile

@@ -0,0 +1,68 @@
+BINDIR      := $(CURDIR)/bin
+INSTALL_PATH ?= /usr/local/bin
+DIST_DIRS   := find * -type d -exec
+TARGETS     := darwin/amd64 darwin/arm64 linux/amd64 linux/386 linux/arm linux/arm64 linux/ppc64le linux/s390x windows/amd64
+TARGET_OBJS ?= darwin-amd64.tar.gz darwin-amd64.tar.gz.sha256 darwin-amd64.tar.gz.sha256sum darwin-arm64.tar.gz darwin-arm64.tar.gz.sha256 darwin-arm64.tar.gz.sha256sum linux-amd64.tar.gz linux-amd64.tar.gz.sha256 linux-amd64.tar.gz.sha256sum linux-386.tar.gz linux-386.tar.gz.sha256 linux-386.tar.gz.sha256sum linux-arm.tar.gz linux-arm.tar.gz.sha256 linux-arm.tar.gz.sha256sum linux-arm64.tar.gz linux-arm64.tar.gz.sha256 linux-arm64.tar.gz.sha256sum linux-ppc64le.tar.gz linux-ppc64le.tar.gz.sha256 linux-ppc64le.tar.gz.sha256sum linux-s390x.tar.gz linux-s390x.tar.gz.sha256 linux-s390x.tar.gz.sha256sum windows-amd64.zip windows-amd64.zip.sha256 windows-amd64.zip.sha256sum
+BINNAME     ?= rdpgw
+
+# Rebuild the binary if any of these files change
+SRC := $(shell find . -type f -name '*.go' -print) go.mod go.sum
+
+# Required for globs to work correctly
+SHELL      = /usr/bin/env bash
+
+GIT_COMMIT = $(shell git rev-parse HEAD)
+GIT_SHA    = $(shell git rev-parse --short HEAD)
+GIT_TAG    = $(shell git describe --tags --abbrev=0 --exact-match 2>/dev/null)
+GIT_DIRTY  = $(shell test -n "`git status --porcelain`" && echo "dirty" || echo "clean")
+
+ifdef VERSION
+	BINARY_VERSION = $(VERSION)
+endif
+BINARY_VERSION ?= ${GIT_TAG}
+
+VERSION_METADATA = unreleased
+# Clear the "unreleased" string in BuildMetadata
+ifneq ($(GIT_TAG),)
+	VERSION_METADATA =
+endif
+
+.PHONY: all
+all: mod build
+
+# ------------------------------------------------------------------------------
+#  build
+
+.PHONY: build
+build: $(BINDIR)/$(BINNAME)
+
+$(BINDIR)/$(BINNAME): $(SRC)
+	GOMODULE=on go build $(GOFLAGS) -trimpath -tags '$(TAGS)' -ldflags '$(LDFLAGS)' -o '$(BINDIR)'/$(BINNAME) ./cmd/rdpgw
+
+# ------------------------------------------------------------------------------
+#  install
+
+.PHONY: install
+install: build
+	@install "$(BINDIR)/$(BINNAME)" "$(INSTALL_PATH)/$(BINNAME)"
+
+# ------------------------------------------------------------------------------
+#  mod
+
+.PHONY: mod
+mod:
+	go mod tidy
+
+# ------------------------------------------------------------------------------
+#  clean
+
+.PHONY: clean
+clean:
+	@rm -rf '$(BINDIR)' ./_dist
+
+.PHONY: info
+info:
+	 @echo "Version:           ${VERSION}"
+	 @echo "Git Tag:           ${GIT_TAG}"
+	 @echo "Git Commit:        ${GIT_COMMIT}"
+	 @echo "Git Tree State:    ${GIT_DIRTY}"