Remove ssh-keygen from ssh-keysign project

ssh-keygen isn't needed by ssh-keysign and ssh-keygen.c and
ssh-keysign.c both have main.

Author: dkulwin

contrib/win32/openssh/ssh-keysign.vcxproj

@@ -178,7 +178,6 @@
   <ItemGroup>
     <ClCompile Include="$(OpenSSH-Src-Path)readconf.c" />
     <ClCompile Include="$(OpenSSH-Src-Path)roaming_dummy.c" />
-    <ClCompile Include="$(OpenSSH-Src-Path)ssh-keygen.c" />
     <ClCompile Include="$(OpenSSH-Src-Path)ssh-keysign.c" />
   </ItemGroup>
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />

contrib/win32/openssh/ssh-keysign.vcxproj.filters

@@ -21,9 +21,6 @@
     <ClCompile Include="$(OpenSSH-Src-Path)roaming_dummy.c">
       <Filter>Source Files</Filter>
     </ClCompile>
-    <ClCompile Include="$(OpenSSH-Src-Path)ssh-keygen.c">
-      <Filter>Source Files</Filter>
-    </ClCompile>
     <ClCompile Include="$(OpenSSH-Src-Path)ssh-keysign.c">
       <Filter>Source Files</Filter>
     </ClCompile>