Reduce the propagation of LOCAL_DEX_PREOPT := nostripping

nostripping causes confusing double negatives, allow nostripping
in LOCAL_DEX_PREOPT and DEFAULT_DEX_PREOPT, but convert to
LOCAL_STRIP_DEX outside of dex_preopt_odex_install.mk.

Test: m checkbuild
Change-Id: I996e9258ce20c394900d9fe937d638bc2ab8589d
diff --git a/core/clear_vars.mk b/core/clear_vars.mk
index 07e34e1..bcedaba 100644
--- a/core/clear_vars.mk
+++ b/core/clear_vars.mk
@@ -274,6 +274,7 @@
 LOCAL_STATIC_JAVA_AAR_LIBRARIES:=
 LOCAL_STATIC_JAVA_LIBRARIES:=
 LOCAL_STATIC_LIBRARIES:=
+LOCAL_STRIP_DEX:=
 LOCAL_STRIP_MODULE:=
 LOCAL_SYSTEM_SHARED_LIBRARIES:=none
 LOCAL_TARGET_REQUIRED_MODULES:=
@@ -284,6 +285,7 @@
 LOCAL_TIDY:=
 LOCAL_TIDY_CHECKS:=
 LOCAL_TIDY_FLAGS:=
+LOCAL_UNCOMPRESS_DEX:=
 LOCAL_UNINSTALLABLE_MODULE:=
 LOCAL_UNSTRIPPED_PATH:=
 LOCAL_USE_AAPT2:=$(USE_AAPT2)