package/vulkan-loader: fix x11 handling

Fix the following build failure raised since the addition of the package
in commit 6aa1bc31678ff9f8013084fda34b9f941cc63fc3:

In file included from /home/buildroot/autobuild/run/instance-3/output-1/build/vulkan-loader-1.3.262/loader/extension_manual.h:24,
                 from /home/buildroot/autobuild/run/instance-3/output-1/build/vulkan-loader-1.3.262/loader/extension_manual.c:23:
/home/buildroot/autobuild/run/instance-3/output-1/host/aarch64-buildroot-linux-gnu/sysroot/usr/include/vulkan/vulkan.h:71:10: fatal error: X11/extensions/Xrandr.h: No such file or directory
   71 | #include <X11/extensions/Xrandr.h>
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~

Fixes:
 - http://autobuild.buildroot.org/results/55ddfd44393e3bcc2f25bad2f9ecb7e1b142a985

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Reviewed-by: Adam Duskett <adam.duskett@amarulasolutions.com>
Tested-by: Adam Duskett <adam.duskett@amarulasolutions.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/vulkan-loader/vulkan-loader.mk

@@ -26,13 +26,16 @@ endif
 
 ifeq ($(BR2_PACKAGE_LIBXCB),y)
 VULKAN_LOADER_DEPENDENCIES += libxcb
-VULKAN_LOADER_CONF_OPTS += \
-	-DBUILD_WSI_XCB_SUPPORT=ON \
-	-DBUILD_WSI_XLIB_SUPPORT=ON
+VULKAN_LOADER_CONF_OPTS += -DBUILD_WSI_XCB_SUPPORT=ON
 else
-VULKAN_LOADER_CONF_OPTS += \
-	-DBUILD_WSI_XCB_SUPPORT=OFF \
-	-DBUILD_WSI_XLIB_SUPPORT=OFF
+VULKAN_LOADER_CONF_OPTS += -DBUILD_WSI_XCB_SUPPORT=OFF
+endif
+
+ifeq ($(BR2_PACKAGE_XLIB_LIBX11)$(BR2_PACKAGE_XLIB_LIBXRANDR),yy)
+VULKAN_LOADER_DEPENDENCIES += xlib_libX11 xlib_libXrandr
+VULKAN_LOADER_CONF_OPTS += -DBUILD_WSI_XLIB_SUPPORT=ON
+else
+VULKAN_LOADER_CONF_OPTS += -DBUILD_WSI_XLIB_SUPPORT=OFF
 endif
 
 ifeq ($(BR2_PACKAGE_WAYLAND),y)