ARM CI: fix explicit features dropped

with the commit 6e8a62b (27th Aug 2025) the explicit feature spec was
accidently dropped (missing $@)

Author: MartinPulec

.github/scripts/Linux/arm/build.sh

@@ -22,7 +22,7 @@ export CFLAGS CXXFLAGS
 
 # shellcheck disable=SC2086 # intentional
 set -- $FEATURES
-set -- --enable-sdl=2  # use SDL2 (environment.sh sets sdl=3)
+set -- "$@" --enable-sdl=2  # use SDL2 (environment.sh sets sdl=3)
 set -- "$@" --enable-drm_disp
 
 ./autogen.sh "$@"