Remove passing -forceprocessing flag to R8

R8 ignores the flag

Test: m -j
Change-Id: Id938aa35e87c9c69769a3184dfea06fd02299688
diff --git a/core/java.mk b/core/java.mk
index cbcd1b5..907f2dc 100644
--- a/core/java.mk
+++ b/core/java.mk
@@ -413,8 +413,6 @@
 legacy_proguard_flags += -printmapping $(proguard_dictionary)
 legacy_proguard_flags += -printconfiguration $(proguard_configuration)
 
-common_proguard_flags := -forceprocessing
-
 common_proguard_flag_files := $(BUILD_SYSTEM)/proguard.flags
 ifneq ($(LOCAL_INSTRUMENTATION_FOR)$(filter tests,$(LOCAL_MODULE_TAGS)),)
 common_proguard_flags += -dontshrink # don't shrink tests by default