Mono runtime pack should include include/ directory on desktop, too

[lambdageek]

We include the include/ directory with the mono embedding API headers in the mobile runtime packs, but not the Microsoft.NETCore.App.Runtime.Mono packs

runtime/src/installer/pkg/sfx/Microsoft.NETCore.App/Microsoft.NETCore.App.Runtime.sfxproj

Lines 82 to 86 in 8d7e074

	<RuntimeFiles Condition="'$(TargetsMobile)' == 'true'"
	Include="@(MonoIncludeFiles)"
	ExcludeFromDataFiles="true">
	<TargetPath>runtimes/$(RuntimeIdentifier)/native/include/%(RecursiveDir)</TargetPath>
	</RuntimeFiles>

[lambdageek]

/cc @steveisok