Update NuSpecs for recent SymbolSearch change.

src/NuGet/Microsoft.CodeAnalysis.EditorFeatures.nuspec

@@ -10,6 +10,7 @@ Supported Platforms:
     </description>
     <dependencies>
       <dependency id="Microsoft.CodeAnalysis.Features" version="[$version$]" />
+      <dependency id="Microsoft.CodeAnalysis.Elfie" version="$MicrosoftCodeAnalysisElfieVersion$" />
     </dependencies>
 
     <language>en-US</language>

src/NuGet/Microsoft.CodeAnalysis.Workspaces.Common.nuspec

@@ -21,7 +21,6 @@
       <group targetFramework="net46">
         <dependency id="ManagedEsent" version="$ManagedEsentVersion$" />
         <dependency id="Microsoft.CodeAnalysis.Common" version="[$version$]" />
-        <dependency id="Microsoft.CodeAnalysis.Elfie" version="$MicrosoftCodeAnalysisElfieVersion$" />
         <dependency id="Microsoft.Composition" version="$MicrosoftCompositionVersion$" />
       </group>
     </dependencies>