fix project file.

Author: csyonghe

source/slang/slang.vcxproj

@@ -237,7 +237,6 @@
     <ClCompile Include="syntax.cpp" />
     <ClCompile Include="token.cpp" />
     <ClCompile Include="type-layout.cpp" />
-    <ClCompile Include="val-defs.cpp" />
     <ClCompile Include="vm.cpp" />
   </ItemGroup>
   <ItemGroup>

source/slang/slang.vcxproj.filters

@@ -74,7 +74,6 @@
     <ClCompile Include="ir-legalize-types.cpp" />
     <ClCompile Include="ast-legalize.cpp" />
     <ClCompile Include="legalize-types.cpp" />
-    <ClCompile Include="val-defs.cpp" />
   </ItemGroup>
   <ItemGroup>
     <CustomBuild Include="core.meta.slang" />