tdf#156825 Half of the splash screen is visible on both monitors under Linux

Blind fix, since I don't have two screens.

regression from
    commit 4c00a5bce3
    Author: Noel Grandin <noel.grandin@collabora.co.uk>
    Date:   Thu Jul 20 11:27:17 2023 +0200
    Assume that, if we have X11, it supports Xinerama

It looks like I missed the removal of some USE_XINERAMA pieces

Change-Id: I402db170916efe935d8ff9f96cc9b327070809b7
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/155939
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

desktop/Executable_oosplash.mk

@@ -24,15 +24,9 @@ $(eval $(call gb_Executable_add_cobjects,oosplash,\
 ))
 
 ifneq ($(USING_X11),)
-
-$(eval $(call gb_Executable_add_defs,oosplash,\
-    -DUSE_XINERAMA \
-))
-
 $(eval $(call gb_Executable_add_libs,oosplash,\
     -lXinerama \
 ))
-
 endif
 
 ifneq ($(DISABLE_GUI),TRUE)

desktop/unx/source/splashx.c

@@ -16,9 +16,7 @@
 #include <X11/Xatom.h>
 #include <X11/Xutil.h>
 
-#ifdef USING_X11
 #include <X11/extensions/Xinerama.h>
-#endif
 
 #include <osl/endian.h>
 #include <fcntl.h>
@@ -406,10 +404,8 @@ static int splash_init_display( struct splash* splash, int argc, char** argv )
 {
     char *display_name = NULL;
     int i;
-#ifdef USING_X11
     int n_xinerama_screens = 1;
     XineramaScreenInfo* p_screens = NULL;
-#endif
 
     for ( i = 0; i < argc; i++ )
     {
@@ -442,7 +438,6 @@ static int splash_init_display( struct splash* splash, int argc, char** argv )
     splash->display_x_pos = 0;
     splash->display_y_pos = 0;
 
-#ifdef USING_X11
     p_screens = XineramaQueryScreens( splash->display, &n_xinerama_screens );
     if( p_screens )
     {
@@ -459,7 +454,6 @@ static int splash_init_display( struct splash* splash, int argc, char** argv )
         }
         XFree( p_screens );
     }
-#endif
     return 1;
 }
 
@@ -812,6 +806,6 @@ struct splash* splash_create(rtl_uString* pAppPath, int argc, char** argv)
 }
 
 
-#endif // ENABLE_QUICKSTART_LIBPNG
+#endif // defined(ENABLE_QUICKSTART_LIBPNG) && HAVE_FEATURE_UI
 
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */

solenv/gbuild/PrecompiledHeaders.mk

@@ -149,7 +149,6 @@ gb_PrecompiledHeader_ignore_flags_system := \
 -DSYSTEM_NSS \
 -DHAVE_VALGRIND_HEADERS \
 -DUSE_RANDR \
--DUSE_XINERAMA_XORG \
 -DDISABLE_CVE_TESTS \
 -DCPPUNIT_PLUGIN_EXPORT='extern "C" SAL_DLLPUBLIC_EXPORT' \
 -DOOO_DLLIMPLEMENTATION_TEST \

vcl/Library_vclplug_gen.mk

@@ -134,9 +134,6 @@ endif
 
 ## handle Xinerama
 ifneq ($(USING_X11),)
-$(eval $(call gb_Library_add_defs,vclplug_gen,\
-    -DUSE_XINERAMA_XORG \
-))
 ifeq ($(XINERAMA_LINK),dynamic)
 $(eval $(call gb_Library_add_libs,vclplug_gen,\
     -lXinerama \