current mingw headers don't have fMergeNeutralItems

Reported upstream by Kendy (r5626), for now do not use the field
if not present, seems to be not that important.

config_host/config_mingw.h.in

+#ifndef CONFIG_MINGW
+#define CONFIG_MINGW
+
+#undef HAVE_FMERGENEUTRALITEMS
+
+#endif

configure.ac

@@ -5350,6 +5350,23 @@ using namespace std;
     AC_SUBST(MINGW_GXXDLL)
 fi
 
+if test "$WITH_MINGW" = "yes"; then
+    AC_MSG_CHECKING([for fMergeNeutralItems in SCRIPT_CONTROL])
+    AC_COMPILE_IFELSE([AC_LANG_PROGRAM(
+    [
+    #include <usp10.h>
+    ],
+    [
+    SCRIPT_CONTROL c;
+    c.fMergeNeutralItems = 1;
+    ])],
+    [
+    AC_MSG_RESULT(yes)
+    AC_DEFINE(HAVE_FMERGENEUTRALITEMS)
+    ],
+    [AC_MSG_RESULT(no)])
+fi
+
 dnl ===================================================================
 dnl Extra checking for the SunOS compiler
 dnl ===================================================================
@@ -11842,6 +11859,7 @@ AC_CONFIG_FILES([solenv/inc/minor.mk.tmp:solenv/inc/minor.mk.in],
 AC_CONFIG_HEADERS([config_host/config_clang.h])
 AC_CONFIG_HEADERS([config_host/config_global.h])
 AC_CONFIG_HEADERS([config_host/config_graphite.h])
+AC_CONFIG_HEADERS([config_host/config_mingw.h])
 AC_CONFIG_HEADERS([config_host/config_telepathy.h])
 AC_CONFIG_HEADERS([config_host/config_typesizes.h])
 AC_CONFIG_HEADERS([config_host/config_vclplug.h])

vcl/win/source/gdi/winlayout.cxx

@@ -63,6 +63,8 @@ using ::rtl::OUString;
 using ::rtl::OString;
 using ::rtl::OUStringToOString;
 
+#include <config_mingw.h>
+
 // =======================================================================
 
 // win32 specific physical font instance
@@ -1189,7 +1191,9 @@ bool UniscribeLayout::LayoutText( ImplLayoutArgs& rArgs )
     SCRIPT_CONTROL aScriptControl = {nLangId,false,false,false,false,false,false,false,false,0};
     aScriptControl.fNeutralOverride = aScriptState.fOverrideDirection;
     aScriptControl.fContextDigits   = (0 != (rArgs.mnFlags & SAL_LAYOUT_SUBSTITUTE_DIGITS));
+#ifdef HAVE_FMERGENEUTRALITEMS
     aScriptControl.fMergeNeutralItems = true;
+#endif
     // determine relevant substring and work only on it
     // when Bidi status is unknown we need to look at the whole string though
     mnSubStringMin = 0;