Don't use ziptime with unbundled builds

Some of the trees are unable to compile native code with the normal
build rules, even though they can build kati.

Bug: 24201956
Change-Id: I2afc3468480b2c78407d62323e6b82979c8ee254
diff --git a/core/config.mk b/core/config.mk
index 4839438..5678a83 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -524,7 +524,9 @@
 # dx is java behind a shell script; no .exe necessary.
 DX := $(HOST_OUT_EXECUTABLES)/dx
 ZIPALIGN := $(HOST_OUT_EXECUTABLES)/zipalign$(HOST_EXECUTABLE_SUFFIX)
+ifndef TARGET_BUILD_APPS
 ZIPTIME := $(HOST_OUT_EXECUTABLES)/ziptime$(HOST_EXECUTABLE_SUFFIX)
+endif
 
 # relocation packer
 RELOCATION_PACKER := prebuilts/misc/$(BUILD_OS)-$(HOST_PREBUILT_ARCH)/relocation_packer/relocation_packer
diff --git a/core/definitions.mk b/core/definitions.mk
index ad68688..5a6a411 100644
--- a/core/definitions.mk
+++ b/core/definitions.mk
@@ -2149,9 +2149,11 @@
 
 # Remove dynamic timestamps from packages
 #
+ifndef TARGET_BUILD_APPS
 define remove-timestamps-from-package
 $(hide) $(ZIPTIME) $@
 endef
+endif
 
 # Uncompress shared libraries embedded in an apk.
 #