Visual Studio: make it easier to build with VS

This changes default path to openvpn dependencies, so that
openvpn-build and openvpn projects can be cloned from the same
folder:

  c:\Users\Administrator\Projects>git clone
git@github.com:OpenVPN/openvpn-build.git
  c:\Users\Administrator\Projects>git clone
git@github.com:OpenVPN/openvpn.git

This also removes the necessity of copying openvpn-build\msvc\image
to %USERPROFILE%.

To use Visual Studio, clone both projects, install dependencies
(VS2017 Community with SDK 10.0.17143, Strawberry Perl) and run:

  c:\Users\Administrator\Projects\openvpn-build\msvc\build.bat

Then just open solution file:

  c:\Users\Administrator\Projects\openvpn\openvpn.sln

Signed-off-by: Lev Stipakov <lstipakov@gmail.com>
Acked-by: Simon Rozman <simon@rozman.si>
Message-Id: <1570784625-8837-1-git-send-email-lstipakov@gmail.com>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg18930.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>

src/compat/PropertySheet.props

@@ -3,7 +3,7 @@
   <ImportGroup Label="PropertySheets" />
   <PropertyGroup Label="UserMacros">
     <SOURCEBASE>$(SolutionDir)</SOURCEBASE>
-    <OPENVPN_DEPROOT>$(SOURCEBASE)\..\..\image</OPENVPN_DEPROOT>
+    <OPENVPN_DEPROOT>$(SOURCEBASE)\..\openvpn-build\msvc\image</OPENVPN_DEPROOT>
     <OPENSSL_HOME>$(OPENVPN_DEPROOT)</OPENSSL_HOME>
     <TAP_WINDOWS_HOME>$(OPENVPN_DEPROOT)</TAP_WINDOWS_HOME>
     <LZO_HOME>$(OPENVPN_DEPROOT)</LZO_HOME>