AudioFlinger: re-add viper optimizations

These make a notable difference when playing audio on ESP32.

Without them, each UI action causes a stutter, so it's not fun to listen
to audio while doing anything on the device. With them, most UI actions don't
cause a stutter. Long maxed out CPU runs and storage access still do, though.

scripts/build_mpos.sh

@@ -101,12 +101,23 @@ if [ "$target" == "esp32" ]; then
 elif [ "$target" == "unix" -o "$target" == "macOS" ]; then
 	manifest=$(readlink -f "$codebasedir"/manifests/manifest.py)
 	frozenmanifest="FROZEN_MANIFEST=$manifest"
+
+	# Comment out @micropython.viper decorator for Unix/macOS builds
+	# (cross-compiler doesn't support Viper native code emitter)
+	echo "Temporarily commenting out @micropython.viper decorator for Unix/macOS build..."
+	stream_wav_file="$codebasedir"/internal_filesystem/lib/mpos/audio/stream_wav.py
+	sed -i 's/^@micropython\.viper$/#@micropython.viper/' "$stream_wav_file"
+
 	# LV_CFLAGS are passed to USER_C_MODULES
 	# STRIP= makes it so that debug symbols are kept
 	pushd "$codebasedir"/lvgl_micropython/
 	# USER_C_MODULE doesn't seem to work properly so there are symlinks in lvgl_micropython/extmod/
 	python3 make.py "$target" LV_CFLAGS="-g -O0 -ggdb -ljpeg" STRIP=  DISPLAY=sdl_display INDEV=sdl_pointer INDEV=sdl_keyboard "$frozenmanifest"
 	popd
+
+	# Restore @micropython.viper decorator after build
+	echo "Restoring @micropython.viper decorator..."
+	sed -i 's/^#@micropython\.viper$/@micropython.viper/' "$stream_wav_file"
 else
 	echo "invalid target $target"
 fi