VS: Use absolute target-specific directory for `resources.pri`

The change in commit v3.7.0-rc1~219^2 (VS: Use target-specific directory
for `resources.pri`, 2016-08-25) incorrectly specifies a relative path
for the `ProjectPriFullPath` value.  Fix it to use an absolute path.

Issue: #16106

Source/cmVisualStudio10TargetGenerator.cxx

@@ -2736,8 +2736,10 @@ void cmVisualStudio10TargetGenerator::WriteWinRTPackageCertificateKeyFile()
       (*this->BuildFileStream) << cmVS10EscapeXML(artifactDir)
                                << "\\</AppxPackageArtifactsDir>\n";
       this->WriteString("<ProjectPriFullPath>", 2);
-      (*this->BuildFileStream) << cmVS10EscapeXML(artifactDir)
-                               << "\\resources.pri</ProjectPriFullPath>\n";
+      std::string resourcePriFile =
+        this->DefaultArtifactDir + "/resources.pri";
+      this->ConvertToWindowsSlash(resourcePriFile);
+      (*this->BuildFileStream) << resourcePriFile << "</ProjectPriFullPath>\n";
 
       // If we are missing files and we don't have a certificate and
       // aren't targeting WP8.0, add a default certificate