fix build more (#14)

Makefile

@@ -12,7 +12,7 @@ MD2ROFF_BIN=github.com/davidnewhall/md2roff
 RSRC_BIN=github.com/akavel/rsrc
 
 # If upx is available, use it to compress the binaries.
-UPX=$(shell which upx)
+UPXPATH=$(shell which upx)
 
 # Travis CI passes the version in. Local builds get it from the current git tag.
 ifeq ($(VERSION),)
@@ -128,39 +128,39 @@ $(shell go env GOPATH)/bin/rsrc:
 build: $(BINARY)
 $(BINARY): main.go
 	go build -o $(BINARY) -ldflags "-w -s $(VERSION_LDFLAGS) $(EXTRA_LDFLAGS) "
-	[ "$(UPX)" == "" ] || upx -q9 $@
+	[ -z "$(UPXPATH)" ] || $(UPXPATH) -q9 $@
 
 linux: $(BINARY).amd64.linux
 $(BINARY).amd64.linux: main.go
 	# Building linux 64-bit x86 binary.
 	GOOS=linux GOARCH=amd64 go build -o $@ -ldflags "-w -s $(VERSION_LDFLAGS) $(EXTRA_LDFLAGS) "
-	[ "$(UPX)" == ""] || upx -q9 $@
+	[ -z "$(UPXPATH)" ] || $(UPXPATH) -q9 $@
 
 linux386: $(BINARY).i386.linux
 $(BINARY).i386.linux: main.go
 	# Building linux 32-bit x86 binary.
 	GOOS=linux GOARCH=386 go build -o $@ -ldflags "-w -s $(VERSION_LDFLAGS) $(EXTRA_LDFLAGS) "
-	[ "$(UPX)" == "" ] || upx -q9 $@
+	[ -z "$(UPXPATH)" ] || $(UPXPATH) -q9 $@
 
 arm: arm64 armhf
 
 arm64: $(BINARY).arm64.linux
 $(BINARY).arm64.linux: main.go
 	# Building linux 64-bit ARM binary.
 	GOOS=linux GOARCH=arm64 go build -o $@ -ldflags "-w -s $(VERSION_LDFLAGS) $(EXTRA_LDFLAGS) "
-	[ "$(UPX)" == "" ] || upx -q9 $@
+	[ -z "$(UPXPATH)" ] || $(UPXPATH) -q9 $@
 
 armhf: $(BINARY).armhf.linux
 $(BINARY).armhf.linux: main.go
 	# Building linux 32-bit ARM binary.
 	GOOS=linux GOARCH=arm GOARM=6 go build -o $@ -ldflags "-w -s $(VERSION_LDFLAGS) $(EXTRA_LDFLAGS) "
-	[ "$(UPX)" == "" ] || upx -q9 $@
+	[ -z "$(UPXPATH)" ] || $(UPXPATH) -q9 $@
 
 macos: $(BINARY).amd64.macos
 $(BINARY).amd64.macos: main.go
 	# Building darwin 64-bit x86 binary.
 	GOOS=darwin GOARCH=amd64 go build -o $@ -ldflags "-w -s $(VERSION_LDFLAGS) $(EXTRA_LDFLAGS) "
-	[ "$(UPX)" == "" ] || upx -q9 $@
+	[ -z "$(UPXPATH)" ] || $(UPXPATH) -q9 $@
 
 freebsd: $(BINARY).amd64.freebsd
 $(BINARY).amd64.freebsd: main.go
@@ -169,7 +169,7 @@ $(BINARY).amd64.freebsd: main.go
 freebsd386: $(BINARY).i386.freebsd
 $(BINARY).i386.freebsd: main.go
 	GOOS=freebsd GOARCH=386 go build -o $@ -ldflags "-w -s $(VERSION_LDFLAGS) $(EXTRA_LDFLAGS) "
-	[ "$(UPX)" == "" ] || upx -q9 $@ || true
+	[ -z "$(UPXPATH)" ] || $(UPXPATH) -q9 $@ || true
 
 freebsdarm: $(BINARY).armhf.freebsd
 $(BINARY).armhf.freebsd: main.go
@@ -180,7 +180,7 @@ windows: $(BINARY).amd64.exe
 $(BINARY).amd64.exe: rsrc.syso main.go
 	# Building windows 64-bit x86 binary.
 	GOOS=windows GOARCH=amd64 go build -o $@ -ldflags "-w -s $(VERSION_LDFLAGS) $(EXTRA_LDFLAGS) $(WINDOWS_LDFLAGS)"
-	[ "$(UPX)" == "" ] || upx -q9 $@
+	[ -z "$(UPXPATH)" ] || $(UPXPATH) -q9 $@
 
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