host-local: Update host-local IPAM to support Windows

vendor/github.com/alexflint/go-filemutex/README.md

@@ -0,0 +1,31 @@
+# FileMutex
+
+FileMutex is similar to `sync.RWMutex`, but also synchronizes across processes.
+On Linux, OSX, and other POSIX systems it uses the flock system call. On windows
+it uses the LockFileEx and UnlockFileEx system calls.
+
+```go
+import (
+	"log"
+	"github.com/alexflint/go-filemutex"
+)
+
+func main() {
+	m, err := filemutex.New("/tmp/foo.lock")
+	if err != nil {
+		log.Fatalln("Directory did not exist or file could not created")
+	}
+
+	m.Lock()  // Will block until lock can be acquired
+
+	// Code here is protected by the mutex
+
+	m.Unlock()
+}
+```
+
+### Installation
+
+    go get github.com/alexflint/go-filemutex
+
+Forked from https://github.com/golang/build/tree/master/cmd/builder/filemutex_*.go