Add basic support for FreeBSD.

This commit adds basic support for FreeBSD by adding an
`alias_freebsd.go`.
The only supported backend is the `file` backend when compiled for
FreeBSD.

We also add some `.gitignore` entries for vim backup files and add
entries to the `Makefile` to compile freebsd-{389,amd64} binaries.

.gitignore

@@ -1,3 +1,4 @@
 /aws-vault
 /aws-vault-*
 .DS_Store
+*~

Makefile

@@ -24,7 +24,13 @@ aws-vault-darwin-amd64: $(SRC)
 aws-vault-windows-386.exe: $(SRC)
 	GOOS=windows GOARCH=386 go build -o $@ -ldflags="$(FLAGS)" .
 
-release: aws-vault-linux-amd64 aws-vault-darwin-amd64 aws-vault-windows-386.exe
+aws-vault-freebsd-386: $(SRC)
+	GOOS=freebsd GOARCH=386 go build -o $@ -ldflags="$(FLAGS)" .
+
+aws-vault-freebsd-amd64: $(SRC)
+	GOOS=freebsd GOARCH=amd64 go build -o $@ -ldflags="$(FLAGS)" .
+
+release: aws-vault-linux-amd64 aws-vault-darwin-amd64 aws-vault-windows-386.exe aws-vault-freebsd-386 aws-vault-freebsd-amd64
 
 clean:
-	rm -f aws-vault aws-vault-linux-amd64 aws-vault-darwin-amd64 aws-vault-windows-386.exe
+	rm -f aws-vault aws-vault-linux-amd64 aws-vault-darwin-amd64 aws-vault-windows-386.exe aws-vault-freebsd-386 aws-vault-freebsd-amd64

server/alias_freebsd.go

@@ -0,0 +1,9 @@
+// build: freebsd
+
+package server
+
+import "os/exec"
+
+func installNetworkAlias() ([]byte, error) {
+	return exec.Command("ifconfig", "lo0", "alias", "169.254.169.254").CombinedOutput()
+}