datapath-windows: Specify external include paths

VStudio 16.10 adds usermode includes before including the driver kit ones.

Bug tracked at:
https://developercommunity.visualstudio.com/t/error-lnk2019-unresolved-external-symbol-stdio-com/1434674

Fixes appveyor build reported by forcing external includes.

Reported-by: Ilya Maximets <i.maximets@ovn.org>
Reported-by: Frank Wagner <frank.wagner@dbosoft.eu>
Reported-at: openvswitch/ovs-issues#209 (comment)
Reported-at: openvswitch/ovs-issues#211
Signed-off-by: Alin Gabriel Serdean <aserdean@ovn.org>
Acked-by: Ilya Maximets <i.maximets@ovn.org>

datapath-windows/ovsext/ovsext.vcxproj

@@ -192,22 +192,39 @@
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Win10 Release|x64'">
     <Inf2CatUseLocalTime>true</Inf2CatUseLocalTime>
+    <ExternalIncludePath>$(CRT_IncludePath);$(KM_IncludePath);</ExternalIncludePath>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Win10 Debug|x64'">
     <Inf2CatUseLocalTime>true</Inf2CatUseLocalTime>
+    <ExternalIncludePath>$(CRT_IncludePath);$(KM_IncludePath);</ExternalIncludePath>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Win10Analyze|x64'">
     <Inf2CatUseLocalTime>true</Inf2CatUseLocalTime>
     <CodeAnalysisRuleSet>..\misc\DriverRecommendedRules.ruleset</CodeAnalysisRuleSet>
     <RunCodeAnalysis>true</RunCodeAnalysis>
+    <ExternalIncludePath>$(CRT_IncludePath);$(KM_IncludePath);</ExternalIncludePath>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Win8.1Analyze|x64'">
     <RunCodeAnalysis>true</RunCodeAnalysis>
     <CodeAnalysisRuleSet>..\misc\DriverRecommendedRules.ruleset</CodeAnalysisRuleSet>
+    <ExternalIncludePath>$(CRT_IncludePath);$(KM_IncludePath);</ExternalIncludePath>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Win8Analyze|x64'">
     <RunCodeAnalysis>true</RunCodeAnalysis>
     <CodeAnalysisRuleSet>..\misc\DriverRecommendedRules.ruleset</CodeAnalysisRuleSet>
+    <ExternalIncludePath>$(CRT_IncludePath);$(KM_IncludePath);</ExternalIncludePath>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Win8 Debug|x64'">
+    <ExternalIncludePath>$(CRT_IncludePath);$(KM_IncludePath);</ExternalIncludePath>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Win8 Release|x64'">
+    <ExternalIncludePath>$(CRT_IncludePath);$(KM_IncludePath);</ExternalIncludePath>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Win8.1 Debug|x64'">
+    <ExternalIncludePath>$(CRT_IncludePath);$(KM_IncludePath);</ExternalIncludePath>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Win8.1 Release|x64'">
+    <ExternalIncludePath>$(CRT_IncludePath);$(KM_IncludePath);</ExternalIncludePath>
   </PropertyGroup>
   <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Win8 Release|x64'">
     <ClCompile>