[wasm] Fix order of include paths, to have the obj dir first

this regressed recently, and we started using `pinvoke-table.h`, and
`icall-table.h` from the runtime pack instead of from the obj dir.

src/mono/wasm/build/WasmApp.targets

@@ -464,18 +464,17 @@
    <Error Condition="'$(RunAOTCompilation)' == 'true' and @(_BitcodeFile->Count()) != @(_AOTAssemblies->Count())"
           Text="Bug: Number of aot assemblies doesn't match the number of generated bitcode files. BitcodeFiles: @(_BitcodeFile->Count()) vs Assemblies: @(_AOTAssemblies->Count())" />
 
+   <ItemGroup>
+     <_EmccIncludePaths Include="$(_WasmIntermediateOutputPath.TrimEnd('\/'))" />
+     <_EmccIncludePaths Include="$(_WasmIncludeDir)mono-2.0" />
+     <_EmccIncludePaths Include="$(_WasmIncludeDir)wasm" />
+   </ItemGroup>
+
    <PropertyGroup>
-     <EmccCFlags>$(EmccFlags) -DCORE_BINDINGS -DGEN_PINVOKE=1 "-I$(_WasmIncludeDir)mono-2.0" "-I$(_WasmIncludeDir)wasm"</EmccCFlags>
+     <EmccCFlags>$(EmccFlags) -DCORE_BINDINGS -DGEN_PINVOKE=1</EmccCFlags>
+     <EmccCFlags>$(EmccCFlags) @(_EmccIncludePaths -> '&quot;-I%(Identity)&quot;', ' ')</EmccCFlags>
      <EmccCFlags Condition="'$(WasmNativeDebugSymbols)' == 'true'">$(EmccCFlags) -g</EmccCFlags>
 
-     <!--
-          For path c:\foo\bar\ quoting would make it "c:\foo\bar\"
-          .. which escapes the closing quote. So, instead make it
-            c:\foo\bar\ -> "c:\foo\bar\."
-     -->
-     <EmccCFlags Condition="$(_WasmIntermediateOutputPath.EndsWith('\')) ">$(EmccCFlags) "-I$(_WasmIntermediateOutputPath)."</EmccCFlags>
-     <EmccCFlags Condition="!$(_WasmIntermediateOutputPath.EndsWith('\'))">$(EmccCFlags) "-I$(_WasmIntermediateOutputPath)"</EmccCFlags>
-
      <EmccLDFlags>$(EmccFlags) -s TOTAL_MEMORY=536870912</EmccLDFlags>
      <_WasmOptCommand>$([MSBuild]::NormalizePath('$(EmSdkUpstreamBinPath)', 'wasm-opt$(_ExeExt)'))</_WasmOptCommand>
    </PropertyGroup>