[Makefile] quote command args

Prevent build error when e.g. 1) git is not available, 2) source folder is not a git repo (downloaded from GitHub archive).

Makefile

@@ -73,9 +73,9 @@ all: haxe tools
 haxe:
 	$(DUNE_COMMAND) build --workspace dune-workspace.dev src-prebuild/prebuild.exe
 	_build/default/src-prebuild/prebuild.exe libparams $(LIB_PARAMS) > lib.sexp
-	_build/default/src-prebuild/prebuild.exe version $(ADD_REVISION) $(BRANCH) $(COMMIT_SHA) > src/compiler/version.ml
+	_build/default/src-prebuild/prebuild.exe version "$(ADD_REVISION)" "$(BRANCH)" "$(COMMIT_SHA)" > src/compiler/version.ml
 	$(DUNE_COMMAND) build --workspace dune-workspace.dev src/haxe.exe
-	cp -f _build/default/src/haxe.exe ./${HAXE_OUTPUT}
+	cp -f _build/default/src/haxe.exe ./"$(HAXE_OUTPUT)"
 
 plugin: haxe
 	$(DUNE_COMMAND) build --workspace dune-workspace.dev plugins/$(PLUGIN)/$(PLUGIN).cmxs