Trim compiled unit export surface

scripts/compile_wasm_unit

@@ -20,7 +20,7 @@ PCH_ENABLED=${UCE_WASM_UNIT_PCH:-1}
 PCH_DIR=${UCE_WASM_PCH_DIR:-/tmp/uce/wasm-w2/pch}
 COMMON_FLAGS=(
 	--target=wasm32-wasip1
-	-fPIC -fvisibility=default -fvisibility-inlines-hidden
+	-fPIC -fvisibility=hidden -fvisibility-inlines-hidden
 	-O1 -g -std=c++20
 	# The server captures this script's output and treats any non-empty result as
 	# a compile failure (then drops the .wasm), so a successful build must be
@@ -80,6 +80,7 @@ fi
 	-c "$DEST_DIR/$PP_FN" -o "$OBJ_FN"
 
 "$SDK/bin/wasm-ld" -shared --experimental-pic \
+	--gc-sections \
 	--unresolved-symbols=import-dynamic \
 	--Bsymbolic \
 	"$OBJ_FN" -o "$WASM_TMP" \
@@ -92,7 +93,7 @@ fi
 	--export-if-defined=__uce_once \
 	--export-if-defined=__uce_init
 
-"$SDK/bin/llvm-objcopy" --add-section=uce.abi="$ABI_TMP" "$WASM_TMP"
+"$SDK/bin/llvm-objcopy" --strip-debug --add-section=uce.abi="$ABI_TMP" "$WASM_TMP"
 
 python3 scripts/check_unit_wasm.py "$WASM_TMP" --abi-version "$ABI_VERSION" --llvm-nm "$SDK/bin/llvm-nm"
 mv "$WASM_TMP" "$DEST_DIR/$WASM_FN"