Fix "conflicting targets" warning when generating VS projects

The VS project generator never calls the Win32MakefileGenerator code
that sets up DEST_TARGET which is used for checking for conflicting
DESTDIR/TARGET combinations on Windows. Replicate the setup in
VcprojGenerator::initProject().

This amends commit e75aed1a.

Change-Id: I4238eb2f57615095c372cee9ada9fc961cc36133
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>

qmake/generators/win32/msvc_vcproj.cpp

@@ -940,6 +940,15 @@ void VcprojGenerator::initProject()
     vcProject.SccProjectName = project->first("SCCPROJECTNAME").toQString();
     vcProject.SccLocalPath = project->first("SCCLOCALPATH").toQString();
     vcProject.flat_files = project->isActiveConfig("flat");
+
+    // Set up the full target path for target conflict checking.
+    const QChar slash = QLatin1Char('/');
+    QString destdir = QDir::fromNativeSeparators(var("DESTDIR"));
+    if (!destdir.endsWith(slash))
+        destdir.append(slash);
+    project->values("DEST_TARGET") = ProStringList(destdir
+                                                   + project->first("TARGET")
+                                                   + project->first("TARGET_EXT"));
 }
 
 void VcprojGenerator::initConfiguration()