Don't make dexpreopt_tools.zip when dex2oat isn't avilable

Test: m
Bug: 158843648
Change-Id: Iae90ea60fc73f1a6202499528277fce7c950d9d3
diff --git a/core/Makefile b/core/Makefile
index 8a51c1f..26b19c0 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -5321,6 +5321,7 @@
 
 # The mac build doesn't build dex2oat, so create the zip file only if the build OS is linux.
 ifeq ($(BUILD_OS),linux)
+ifneq ($(DEX2OAT),)
 dexpreopt_tools_deps := $(DEXPREOPT_GEN_DEPS) $(DEXPREOPT_GEN) $(AAPT2)
 DEXPREOPT_TOOLS_ZIP := $(PRODUCT_OUT)/dexpreopt_tools.zip
 $(DEXPREOPT_TOOLS_ZIP): $(dexpreopt_tools_deps)
@@ -5328,7 +5329,8 @@
 $(DEXPREOPT_TOOLS_ZIP): $(SOONG_ZIP)
 	$(hide) mkdir -p $(dir $@)
 	$(hide) $(SOONG_ZIP) -d -o $@ -j $(addprefix -f ,$(PRIVATE_DEXPREOPT_TOOLS_DEPS)) -f $$(realpath $(DEX2OAT))
-endif
+endif # DEX2OAT is set
+endif # BUILD_OS == linux
 
 DEXPREOPT_CONFIG_ZIP := $(PRODUCT_OUT)/dexpreopt_config.zip
 $(DEXPREOPT_CONFIG_ZIP): $(FULL_SYSTEMIMAGE_DEPS) \