OpenXML not compiling in .NET Native

[twsouthwick]

From @prairiesnpr on #168:

I'm unable to compile in release mode with UWP. I receive an ILT0005 error. This is with VS2017RC and NETCore.UniversalWindowsPlatform 5.3.0. Get the same error with 2.7.1 or 2.7.2 -vnext0023. Remove OpenXml or compile in debug and the app will compile.

Error is:
.nuget\packages\microsoft.net.native.compiler\1.6.0\tools\Microsoft.NetNative.targets(691,5): error : ILT0005: .nuget\packages\microsoft.net.native.compiler\1.6.0\tools\x64\ilc\Tools\nutc_driver.exe @"\obj\x64\Release\ilc\intermediate\MDIL\FirearmDb.rsp"' returned exit code 1