Exclude go files for other OS and ARCH in GoNamesCache

This will dramatically increase resolving speed for files that imports "runtime", "syscall", "net", etc.
And also remove duplication in completion list.

The target OS/ARCH in GoSdkData is actually host OS/ARCH, but if user want to develop for other OS/ARCH, he can set environment variable "GOOS"/"GOARCH", then those will be used to exclude files.