-Werror,-Wunused-macros (clang-cl)

...which started to hit me now either due to building against a recent Visual
Studio 2022 Preview 17.4 (which would presumably no longer define those macros
in some system headers, so that the #ifndef's started to kick in now), or due to
building against a more recent Windows SDK (see below), no idea which.

But just dropping the seemingly unused macro definitions from the various .cxx
caused builds against old Windows SDK versions like Jenkins
<https://ci.libreoffice.org/job/gerrit_windows/139228/> to fail like

> C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\um\GdiplusTypes.h(479): error C3861: 'min': identifier not found
> C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\um\GdiplusTypes.h(480): error C3861: 'min': identifier not found
> C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\um\GdiplusTypes.h(481): error C3861: 'max': identifier not found
> C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\um\GdiplusTypes.h(482): error C3861: 'max': identifier not found
> C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\um\GdiplusTypes.h(503): error C3861: 'max': identifier not found
> C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\um\GdiplusTypes.h(504): error C3861: 'max': identifier not found
> C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\um\GdiplusTypes.h(505): error C3861: 'min': identifier not found
> C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\um\GdiplusTypes.h(506): error C3861: 'min': identifier not found
> C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\um\GdiplusTypes.h(667): error C3861: 'min': identifier not found
> C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\um\GdiplusTypes.h(668): error C3861: 'min': identifier not found
> C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\um\GdiplusTypes.h(669): error C3861: 'max': identifier not found
> C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\um\GdiplusTypes.h(670): error C3861: 'max': identifier not found
> C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\um\GdiplusTypes.h(691): error C3861: 'max': identifier not found
> C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\um\GdiplusTypes.h(692): error C3861: 'max': identifier not found
> C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\um\GdiplusTypes.h(693): error C3861: 'min': identifier not found
> C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\um\GdiplusTypes.h(694): error C3861: 'min': identifier not found
[...]
> make[1]: *** [C:/cygwin/home/tdf/jenkins/workspace/gerrit_windows/solenv/gbuild/LinkTarget.mk:334: C:/cygwin/home/tdf/jenkins/workspace/gerrit_windows/workdir/CxxObject/vcl/win/app/salinst.o] Error 2

so move those macro definitions to prewin.h (where they don't trigger clang-cl's
-Werror,-Wunused-macros from within an include file, even if they happen to be
unused in a translation unit).  (For simplicity, see whether it works in
practice to drop those #ifndef wrappers.  If they turn out to be relevant for
some build scenarios after all, they can be added back.)

Change-Id: I76d8794ae2de310bdca420e5488db2bc19de23ca
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/142090
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

include/postwin.h

@@ -51,6 +51,8 @@
 #undef WB_LEFT
 #undef WB_RIGHT
 #undef Yield
+#undef max
 #undef mciSetCommand
+#undef min
 
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */

include/prewin.h

@@ -44,6 +44,17 @@
 
 #include <commctrl.h>
 
+// For some old versions of the Windows SDK, at least GidplusTypes.h (as indirectly included from
+// gdiplus.h, which in turn we often include from between these prewin.h/postwin.h wrappers) expects
+// pre-existing min and max.  That is true for e.g.
+// C:/Program Files (x86)/Windows Kits/10/Include/10.0.19041.0/um/GdiplusTypes.h, but not for e.g.
+// C:/Program Files (x86)/Windows Kits/10/Include/10.0.22000.0/um/GdiplusTypes.h which explicitly
+// defines its own GDIPLUS_MIN/MAX macros.  The easiest fix appears to be to define min/max here and
+// to undefin them again in postwin.h, until no supported version of the Windows SDK requires this
+// hack any longer:
+#define min(a, b) (((a) < (b)) ? (a) : (b))
+#define max(a, b) (((a) > (b)) ? (a) : (b))
+
 #endif
 
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */

vcl/win/app/salinst.cxx

@@ -64,15 +64,6 @@
 
 #include <desktop/crashreport.hxx>
 
-#if defined _MSC_VER
-#ifndef min
-#define min(a,b)    (((a) < (b)) ? (a) : (b))
-#endif
-#ifndef max
-#define max(a,b)    (((a) > (b)) ? (a) : (b))
-#endif
-#endif
-
 #include <prewin.h>
 
 #include <gdiplus.h>

vcl/win/gdi/gdiimpl.cxx

@@ -49,15 +49,6 @@
 #include <win/salids.hrc>
 #include <ControlCacheKey.hxx>
 
-#if defined _MSC_VER
-#ifndef min
-#define min(a,b)    (((a) < (b)) ? (a) : (b))
-#endif
-#ifndef max
-#define max(a,b)    (((a) > (b)) ? (a) : (b))
-#endif
-#endif
-
 #include <prewin.h>
 
 #include <gdiplus.h>

vcl/win/gdi/salbmp.cxx

@@ -35,15 +35,6 @@
 #include <tools/helpers.hxx>
 #include <map>
 
-#if defined _MSC_VER
-#ifndef min
-#define min(a,b)    (((a) < (b)) ? (a) : (b))
-#endif
-#ifndef max
-#define max(a,b)    (((a) > (b)) ? (a) : (b))
-#endif
-#endif
-
 #include <prewin.h>
 #include <gdiplus.h>
 #include <postwin.h>