make binary name .exe for windows

Makefile

@@ -13,14 +13,18 @@ PLATFORMS= \
 	darwin-amd64 \
 	$(NULL)
 
+NAME=jira
+
 OS=$(shell uname -s)
 ifeq ($(filter CYGWIN%,$(OS)),$(OS))
 export CWD=$(shell cygpath -wa .)
 export SEP=\\
 export CYGWIN=winsymlinks:native
+BIN ?= $(GOBIN)$(SEP)$(NAME).exe
 else
 export CWD=$(shell pwd)
 export SEP=/
+BIN ?= $(GOBIN)$(SEP)$(NAME)
 endif
 
 export GOPATH=$(CWD)
@@ -28,9 +32,7 @@ export GOPATH=$(CWD)
 DIST=$(CWD)$(SEP)dist
 
 GOBIN ?= $(CWD)
-NAME=jira
 
-BIN ?= $(GOBIN)$(SEP)$(NAME)
 
 CURVER ?= $(shell [ -d .git ] && git describe --abbrev=0 --tags || grep ^\#\# CHANGELOG.md | awk '{print $$2; exit}')
 LDFLAGS:=-X jira.VERSION=$(patsubst v%,%,$(CURVER)) -w