Rename r8 to r8-compat-proguard

Test: USE_R8=false USE_D8=true m -j32 && USE_R8=true USE_D8=true m -j32

Change-Id: I2610340cf75f8db5920e33fac542f0dcf294ce29
diff --git a/core/definitions.mk b/core/definitions.mk
index c7799b0..8b4051d 100644
--- a/core/definitions.mk
+++ b/core/definitions.mk
@@ -2795,7 +2795,7 @@
 ###########################################################
 define transform-jar-to-dex-r8
 @echo R8: $@
-$(hide) $(JAVA) -jar $(R8_COMPAT_PROGUARD_JAR) -injars '$<$(PRIVATE_PROGUARD_INJAR_FILTERS)' \
+$(hide) $(R8_COMPAT_PROGUARD) -injars '$<$(PRIVATE_PROGUARD_INJAR_FILTERS)' \
     --min-api $(PRIVATE_MIN_SDK_VERSION) \
     --force-proguard-compatibility --output $(subst classes.dex,,$@) \
     $(PRIVATE_PROGUARD_FLAGS) \