vsdownload: Filter packages based on their arch information

[huangqinjin]

Depends on #148.

Match host arch with chip, machineArch and productArch.

PR #148

Selected 475 packages, for a total download size of 2.7 GB, install size of 8.5 GB

PR #149 matching host arch exactly

Selected 449 packages, for a total download size of 2.5 GB, install size of 8.2 GB

EDIT: We go matching host arch exactly.

PR #149

Selected 463 packages, for a total download size of 2.6 GB, install size of 8.3 GB

Current implementation apply the knownledge that

1. x64 host can run x86 binaries
2. arm64 host can run x86/x64 binaries

Otherwise some packages will be incomplete. E.g. package Microsoft.VisualStudio.Debugger.Remote on ARM64:

./vsdownload.py --accept-license --host-arch arm64 --print-deps-tree Microsoft.VisualStudio.Debugger.Remote

Microsoft.VisualStudio.Debugger.Remote
  Microsoft.VisualStudio.Debugger.Remote.Resources (chip.x64)
    Microsoft.VisualStudio.Debugger.Remote.Resources (chip.x86)
  Microsoft.VisualStudio.Debugger.Remote (chip.x86)
    Microsoft.VisualStudio.Debugger.Remote.Resources (chip.x86)
    Microsoft.VisualStudio.Debugger.Concord.Remote (chip.x86)
      Microsoft.VisualStudio.Debugger.Concord.Remote.Resources (chip.x86)
    Microsoft.VisualStudio.Debugger.Remote.DbgHelp.Win8 (chip.x86)
    Microsoft.VisualStudio.Debugger.Remote.ARM64
      Microsoft.VisualStudio.Debugger.Remote.Resources.ARM64
      Microsoft.VisualStudio.Debugger.Remote.ARM (machineArch.ARM64)
        Microsoft.VisualStudio.Debugger.Remote.Resources.ARM
        Microsoft.VisualStudio.Debugger.Concord.Remote.ARM (machineArch.ARM64)
          Microsoft.VisualStudio.Debugger.Concord.Remote.Resources.ARM
      Microsoft.VisualStudio.Debugger.Concord.Remote.ARM64 (machineArch.ARM64)
        Microsoft.VisualStudio.Debugger.Concord.Remote.Resources.ARM64
  Microsoft.VisualStudio.Debugger.Remote.DbgHelp.Win8 (chip.x64)
  Microsoft.VisualStudio.Debugger.Concord.Remote (chip.x64)
    Microsoft.VisualStudio.Debugger.Concord.Remote.Resources

But I think matching host arch exactly is also acceptable, and user need to specify Microsoft.VisualStudio.Debugger.Remote.ARM64 instead of Microsoft.VisualStudio.Debugger.Remote.

[huangqinjin]

The example in the description is actually not correct. Microsoft.VisualStudio.Debugger.Remote on ARM64 have the properties

			"chip": "x64",
			"productArch": "neutral",
			"machineArch": "arm64",

So this package is not for pure ARM64. So anyway Microsoft.VisualStudio.Debugger.Remote.ARM64 is needed for a complete ARM64 Remote Debugger.

So I am going the implement the filter matching host arch exactly.

[huangqinjin]

matching host arch exactly

Selected 450 packages, for a total download size of 2.5 GB, install size of 8.2 GB

[mstorsjo]

The changes look good overall, except for the cosmetic issue

[mstorsjo]

LGTM