break up event-log-tags; generate java source files with constants

Construct the /system/etc/event-log-tags file by unioning together any
*.logtags files included in LOCAL_SRC_FILES throughout the system (with
appropriate error checking for dup tag numbers, etc.)

For java packages, generate a java source file from the logtags file for
that package that contains static integer constants for each tag name.
diff --git a/core/definitions.mk b/core/definitions.mk
index 06b6201..61bd562 100644
--- a/core/definitions.mk
+++ b/core/definitions.mk
@@ -717,6 +717,16 @@
 #$(AIDL) $(PRIVATE_AIDL_FLAGS) $< - | indent -nut -br -npcs -l1000 > $@
 
 
+###########################################################
+## Commands for running java-event-log-tags.py
+###########################################################
+
+define transform-logtags-to-java
+@mkdir -p $(dir $@)
+@echo "logtags: $@ <= $<"
+$(hide) $(JAVATAGS) -o $@ $<
+endef
+
 
 ###########################################################
 ## Commands for running gcc to compile a C++ file