Fix condition used to find VS 2015 Enterprise

The condition used to find whether Visual Studio 2015 Enterprise is
installed was incorrect as the registry key for Enterprise does not
follow the same format as Community and Professional.
This commit addresses a regression introduced by the fix for #19.

src/SqlLocalDb.msbuild

@@ -127,8 +127,8 @@
       <!--
         SKUs of Visual Studio 2015 below Enterprise do not have the appropriate code coverage adapter installed.
       -->
-      <_IsVSEnterprise Condition="'$(Registry:HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\VisualStudio\14.0\Setup\vs\Enterprise@ProductDir)' != ''">true</_IsVSEnterprise>
-      <_IsVSEnterprise Condition="'$(_IsVSEnterprise)' == '' and '$(Registry:HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\VisualStudio\14.0\Setup\vs\Enterprise@ProductDir)' != ''">true</_IsVSEnterprise>
+      <_IsVSEnterprise Condition="'$(Registry:HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\VisualStudio\14.0\Setup\vs\Enterprise@InstallResult)' != ''">true</_IsVSEnterprise>
+      <_IsVSEnterprise Condition="'$(_IsVSEnterprise)' == '' and '$(Registry:HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\VisualStudio\14.0\Setup\vs\Enterprise@InstallResult)' != ''">true</_IsVSEnterprise>
       <_IsVSEnterprise Condition="'$(_IsVSEnterprise)' == ''">false</_IsVSEnterprise>
       <!--
         AppVeyor has Visual Studio Test Agents installed, so can provide code coverage.