vcl: tweak some optional usage of Windows 7 or later symbols...

... so that -D_WIN32_WINNT=0x0502 does not break the build.

Change-Id: I423ba9c194dc4928d59e1713255bce9c3150bcc2

vcl/source/gdi/pdfwriter_impl.cxx

@@ -85,6 +85,10 @@
 
 #ifdef _WIN32
 // WinCrypt headers for PDF signing
+// Note: this uses Windows 7 APIs and requires the relevant data types;
+// the functions that don't exist in WinXP must be looked up at runtime!
+#undef _WIN32_WINNT
+#define _WIN32_WINNT _WIN32_WINNT_WIN7
 #include <prewin.h>
 #include <wincrypt.h>
 #include <postwin.h>

vcl/win/source/app/salinst.cxx

@@ -1001,6 +1001,11 @@ void WinSalInstance::AddToRecentDocumentList(const OUString& rFileUrl, const OUS
                         OUString sApplicationID("TheDocumentFoundation.LibreOffice.");
                         sApplicationID += sApplicationName;
 
+#if _WIN32_WINNT < _WIN32_WINNT_WIN7
+// just define Windows 7 only constant locally...
+#define SHARD_APPIDINFO  0x00000004
+#endif
+
                         typedef struct {
                             IShellItem *psi;
                             PCWSTR     pszAppID;