message: build, qt: Drop unused CROSS_COMPILE variable for Android builds
  Since Qt 5.14.0 the CROSS_COMPILE variable always being overridden by
  the Qt build system internally.
  See upstream commit:
diff: @@ -167,7 +167,6 @@ $(package)_config_opts_android = -xplatform android-clang
  $(package)_config_opts_android += -android-sdk $(ANDROID_SDK)
  $(package)_config_opts_android += -android-ndk $(ANDROID_NDK)
  $(package)_config_opts_android += -android-ndk-platform android-$(ANDROID_API_LEVEL)
  -$(package)_config_opts_android += -device-option CROSS_COMPILE="$(host)-"
  $(package)_config_opts_android += -egl
  $(package)_config_opts_android += -qpa xcb
  $(package)_config_opts_android += -no-dbus
  