Do not check GUI libs for DRM (#4792)

Signed-off-by: Slendi <slendi@socopon.com>

CMakeLists.txt

@@ -37,7 +37,7 @@ include(CompilerFlags)
 # Registers build options that are exposed to cmake
 include(CMakeOptions.txt)
 
-if (UNIX AND NOT APPLE)
+if (UNIX AND NOT APPLE AND NOT "${PLATFORM}" MATCHES "DRM")
   if (NOT GLFW_BUILD_WAYLAND AND NOT GLFW_BUILD_X11)
     MESSAGE(FATAL_ERROR "Cannot disable both Wayland and X11")
   endif()